diff --git a/app.arc b/app.arc
index 6adc8ed533..282fee09a1 100644
--- a/app.arc
+++ b/app.arc
@@ -76,7 +76,7 @@ legacy_users
 email_notification_subscription
   topic *String
   name byTopic
-  
+
 email_notification
   recipient *String
   name byRecipient
diff --git a/app/components/ClientSampleCode.tsx b/app/components/ClientSampleCode.tsx
index abbe07ce54..24401bc1d6 100644
--- a/app/components/ClientSampleCode.tsx
+++ b/app/components/ClientSampleCode.tsx
@@ -473,7 +473,7 @@ export function ClientSampleCode({
             listTopics
               ? `
               // List all topics
-              consumer.Subscription.ForEach(topic => Console.WriteLine(topic));    
+              consumer.Subscription.ForEach(topic => Console.WriteLine(topic));
               `
               : ''
           }
diff --git a/app/components/NoticeTypeCheckboxes/NoticeTypeCheckboxes.tsx b/app/components/NoticeTypeCheckboxes/NoticeTypeCheckboxes.tsx
index 5b75d1bfc1..8a2ef33a1f 100644
--- a/app/components/NoticeTypeCheckboxes/NoticeTypeCheckboxes.tsx
+++ b/app/components/NoticeTypeCheckboxes/NoticeTypeCheckboxes.tsx
@@ -183,11 +183,15 @@ const NoticeTypeLinks: { [key: string]: string | undefined } = {
 }
 
 const JsonNoticeTypes = {
+  IceCube: ['gcn.notices.icecube.LvkNuTrackSearch'],
   LVK: ['igwn.gwalert'],
+  Swift: ['gcn.notices.swift.bat.guano.Alert'],
 }
 
 const JsonNoticeTypeLinks: { [key: string]: string | undefined } = {
+  IceCube: '/missions/icecube',
   LVK: 'https://emfollow.docs.ligo.org/userguide/tutorial/receiving/gcn.html#receiving-and-parsing-notices',
+  Swift: '/missions/swift',
 }
 
 interface NoticeTypeCheckboxProps {
@@ -230,6 +234,7 @@ export function NoticeTypeCheckboxes({
   return (
     <>
       <NestedCheckboxes
+        key={selectedFormat}
         nodes={Object.entries(
           selectedFormat == 'json' ? JsonNoticeTypes : NoticeTypes
         ).map(([mission, noticeTypes]) => ({
diff --git a/app/components/nested-checkboxes/NestedCheckboxes.tsx b/app/components/nested-checkboxes/NestedCheckboxes.tsx
index 57d005edef..152f205e74 100644
--- a/app/components/nested-checkboxes/NestedCheckboxes.tsx
+++ b/app/components/nested-checkboxes/NestedCheckboxes.tsx
@@ -112,7 +112,7 @@ function NestedCheckboxNode({
       />
       <ul hidden={!expanded} className={styles.leaf}>
         {nodes.map((node, index) => (
-          <li role="treeitem" key={index} aria-selected={false}>
+          <li role="treeitem" key={node.id} aria-selected={false}>
             <Checkbox
               {...node}
               inputRef={(instance) => {
@@ -142,9 +142,9 @@ export function NestedCheckboxes({
 }: NestedCheckboxesProps) {
   return (
     <ul role="tree" aria-multiselectable>
-      {nodes.map((node, index) => (
+      {nodes.map((node) => (
         <NestedCheckboxNode
-          key={index}
+          key={node.id}
           {...node}
           childoncheckhandler={childoncheckhandler}
         />
diff --git a/app/email-incoming/circulars/index.ts b/app/email-incoming/circulars/index.ts
index dbebd58b5a..7cc500cdd5 100644
--- a/app/email-incoming/circulars/index.ts
+++ b/app/email-incoming/circulars/index.ts
@@ -159,7 +159,7 @@ function successMessage(
   explanation: string
 ) {
   return `Your GCN Circular from ${userEmail} (subject: ${subject}) was received and distributed.
-  
+
   ${explanation}`
 }
 
@@ -169,7 +169,7 @@ function failedMessage(
   explanation: string
 ) {
   return `Your GCN Circular from ${userEmail} (subject: ${subject}) was not processed for the following reasons:
-  
+
 ${explanation}
 
 If you believe this to be a mistake, please contact us using the form at ${origin}/contact, and we will look into resolving it as soon as possible.`
@@ -184,7 +184,7 @@ const sharedEmailBody = `
 
 
 As of April 12, 2023, GCN Circulars are being administered through the new General Coordinates Network (GCN; ${origin}), and no longer through the GCN Classic service (https://gcn.gsfc.nasa.gov).
-      
+
 The new GCN Circulars allow you to:
 
 - Browse and search Circulars in our all-new archive.
diff --git a/app/routes/api.circulars.ts b/app/routes/api.circulars.ts
index f7cce9d1e6..077edcbbea 100644
--- a/app/routes/api.circulars.ts
+++ b/app/routes/api.circulars.ts
@@ -7,6 +7,7 @@
  */
 import {
   AdminGetUserCommand,
+  AdminListGroupsForUserCommand,
   type AttributeType,
 } from '@aws-sdk/client-cognito-identity-provider'
 import type { ActionFunctionArgs } from '@remix-run/node'
@@ -56,7 +57,6 @@ async function parseAccessToken(jwt: string): Promise<{
   exp: string
   iat: string
   scope: string
-  'cognito:groups': string[]
   username: string
 }> {
   const client = await getOpenIDClient()
@@ -69,7 +69,6 @@ async function parseAccessToken(jwt: string): Promise<{
     'exp',
     'iat',
     'scope',
-    'cognito:groups',
     'username',
   ])
   return payload
@@ -101,6 +100,18 @@ async function getUserAttributes(Username: string) {
   }
 }
 
+async function getUserGroups(Username: string) {
+  const UserPoolId = getEnvOrDie('COGNITO_USER_POOL_ID')
+
+  const { Groups } = await cognito.send(
+    new AdminListGroupsForUserCommand({ UserPoolId, Username })
+  )
+
+  return Groups?.map(({ GroupName }) => GroupName).filter(Boolean) as
+    | string[]
+    | undefined
+}
+
 /**
  * GCN Circulars submission by third parties on behalf of users via an API.
  *
@@ -116,10 +127,10 @@ async function getUserAttributes(Username: string) {
  *      needs to "renew" permission for user account linking
  *    - Allowed callback URLs: must be provided by the third party
  *    - Identity providers: select all
- *    - OpenID Connect Scopes: Phone, Email, OpenID. Do NOT select
+ *    - OpenID Connect Scopes: Phone, Email, OpenID, Profile. Do NOT select
  *      aws.cognito.signin.user.admin.
  *    - Custom scopes: gcn.nasa.gov/circular-submitter
- *    - Attribute read and write permissions: turn off all write permissions
+ *    - Attribute read and write permissions: turn on all
  *
  * 2. We send the client ID, client secret, and OIDC autodiscovery URL to the
  *    third party. The client secret must be encrypted.
@@ -129,8 +140,8 @@ async function getUserAttributes(Username: string) {
  *
  *    a. Do the [authorization code flow] to sign the user in with GCN's IdP.
  *       When requesting the authorization endpoint, be sure to reuqest
- *       scope=gcn.nasa.gov/circular-submitter. (Note: the name of this scope
- *       may change in the future.)
+ *       scope="openid profile gcn.nasa.gov/circular-submitter". (Note: the
+ *       name of the last scope may change in the future.)
  *
  *    b. For now, if resulting ID token contains the 'existingIdp' claim, then
  *       the third party MUST redo the authentication code flow passing the
@@ -163,7 +174,6 @@ export async function action({ request }: ActionFunctionArgs) {
 
   const {
     username: cognitoUserName,
-    'cognito:groups': groups,
     sub,
     scope,
   } = await parseAccessToken(bearer)
@@ -172,7 +182,10 @@ export async function action({ request }: ActionFunctionArgs) {
   if (!scope.split(' ').includes(group))
     throw new Response('Invalid scope', { status: 403 })
 
-  const { existingIdp, ...attrs } = await getUserAttributes(cognitoUserName)
+  const [{ existingIdp, ...attrs }, groups] = await Promise.all([
+    getUserAttributes(cognitoUserName),
+    getUserGroups(cognitoUserName),
+  ])
   if (existingIdp) throw new Response('Wrong IdP', { status: 400 })
 
   const user: User = {
diff --git a/app/routes/circulars.$circularId/AstroData.components.tsx b/app/routes/circulars.$circularId/AstroData.components.tsx
index 9bcbeefcec..73fe4e10b5 100644
--- a/app/routes/circulars.$circularId/AstroData.components.tsx
+++ b/app/routes/circulars.$circularId/AstroData.components.tsx
@@ -5,47 +5,33 @@
  *
  * SPDX-License-Identifier: Apache-2.0
  */
-import { Link } from '@remix-run/react'
+import { AstroDataLink } from './AstroDataContext'
 
 export function GcnCircular({
   children,
   value,
 }: JSX.IntrinsicElements['data']) {
-  return (
-    <Link className="usa-link" to={`/circulars/${value}`}>
-      {children}
-    </Link>
-  )
+  return <AstroDataLink to={`/circulars/${value}`}>{children}</AstroDataLink>
 }
 
 export function Arxiv({ children, value }: JSX.IntrinsicElements['data']) {
   return (
-    <a
-      className="usa-link"
-      rel="external"
-      href={`https://arxiv.org/abs/${value}`}
-    >
+    <AstroDataLink to={`https://arxiv.org/abs/${value}`}>
       {children}
-    </a>
+    </AstroDataLink>
   )
 }
 
 export function Doi({ children, value }: JSX.IntrinsicElements['data']) {
   return (
-    <a className="usa-link" rel="external" href={`https://doi.org/${value}`}>
-      {children}
-    </a>
+    <AstroDataLink to={`https://doi.org/${value}`}>{children}</AstroDataLink>
   )
 }
 
 export function Tns({ children, value }: JSX.IntrinsicElements['data']) {
   return (
-    <a
-      className="usa-link"
-      rel="external"
-      href={`https://www.wis-tns.org/object/${value}`}
-    >
+    <AstroDataLink to={`https://www.wis-tns.org/object/${value}`}>
       {children}
-    </a>
+    </AstroDataLink>
   )
 }
diff --git a/app/routes/circulars.$circularId/AstroDataContext.tsx b/app/routes/circulars.$circularId/AstroDataContext.tsx
new file mode 100644
index 0000000000..08fc0324b4
--- /dev/null
+++ b/app/routes/circulars.$circularId/AstroDataContext.tsx
@@ -0,0 +1,38 @@
+/*!
+ * Copyright © 2023 United States Government as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import { Link, type LinkProps } from '@remix-run/react'
+import classNames from 'classnames'
+import { createContext, useContext } from 'react'
+
+export type AstroDataContextProps = Pick<
+  JSX.IntrinsicElements['a'],
+  'rel' | 'target'
+>
+
+export const AstroDataContext = createContext<AstroDataContextProps>({})
+
+export function AstroDataLink({
+  children,
+  className,
+  rel: origRel,
+  ...props
+}: Omit<LinkProps, 'target'>) {
+  const context = useContext(AstroDataContext)
+  const rel = [origRel, context.rel].filter(Boolean).join(' ') || undefined
+
+  return (
+    <Link
+      className={classNames('usa-link', className)}
+      target={context.target}
+      rel={rel}
+      {...props}
+    >
+      {children}
+    </Link>
+  )
+}
diff --git a/app/routes/circulars.$circularId/PlainTextBody.tsx b/app/routes/circulars.$circularId/Body.tsx
similarity index 62%
rename from app/routes/circulars.$circularId/PlainTextBody.tsx
rename to app/routes/circulars.$circularId/Body.tsx
index ffa0574373..f0779500da 100644
--- a/app/routes/circulars.$circularId/PlainTextBody.tsx
+++ b/app/routes/circulars.$circularId/Body.tsx
@@ -6,15 +6,17 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 import { rehypeAstro } from '@nasa-gcn/remark-rehype-astro'
-import { Link } from '@remix-run/react'
+import classNames from 'classnames'
 import type { Root } from 'mdast'
 import { Fragment, createElement } from 'react'
 import rehypeReact from 'rehype-react'
+import remarkParse from 'remark-parse'
 import remarkRehype from 'remark-rehype'
 import { type Plugin, unified } from 'unified'
 import { u } from 'unist-builder'
 
 import { AstroData } from './AstroData'
+import { AstroDataLink } from './AstroDataContext'
 import rehypeAutolinkLiteral from './rehypeAutolinkLiteral'
 
 import styles from './PlainTextBody.module.css'
@@ -30,16 +32,44 @@ function LinkWrapper({
 }: Omit<JSX.IntrinsicElements['a'], 'ref'>) {
   if (props.href) {
     return (
-      <Link className="usa-link" to={props.href} {...props}>
+      <AstroDataLink to={props.href} {...props}>
         {children}
-      </Link>
+      </AstroDataLink>
     )
   } else {
     return <a {...props}>{children}</a>
   }
 }
 
-export function PlainTextBody({ children }: { children: string }) {
+export function MarkdownBody({
+  className,
+  children,
+}: {
+  className?: string
+  children: string
+}) {
+  const { result } = unified()
+    .use(remarkParse)
+    .use(remarkRehype)
+    .use(rehypeAstro)
+    .use(rehypeAutolinkLiteral)
+    .use(rehypeReact, {
+      Fragment,
+      createElement,
+      components: { a: LinkWrapper, data: AstroData },
+    })
+    .processSync(children)
+
+  return <div className={className}>{result}</div>
+}
+
+export function PlainTextBody({
+  className,
+  children,
+}: {
+  className?: string
+  children: string
+}) {
   const tree = u('root', [u('code', children)])
 
   const { result } = unified()
@@ -54,5 +84,7 @@ export function PlainTextBody({ children }: { children: string }) {
     })
     .processSync()
 
-  return <div className={styles.PlainTextBody}>{result}</div>
+  return (
+    <div className={classNames(styles.PlainTextBody, className)}>{result}</div>
+  )
 }
diff --git a/app/routes/circulars.$circularId/PlainTextBody.module.scss b/app/routes/circulars.$circularId/PlainTextBody.module.scss
index a1f72255c1..4fdf63545d 100644
--- a/app/routes/circulars.$circularId/PlainTextBody.module.scss
+++ b/app/routes/circulars.$circularId/PlainTextBody.module.scss
@@ -6,4 +6,9 @@
     white-space: pre-wrap;
     background: none;
   }
+
+  & pre,
+  &code {
+    margin: 0;
+  }
 }
diff --git a/app/routes/circulars.$circularId/route.tsx b/app/routes/circulars.$circularId/route.tsx
index 5c32b2c166..047ac03bb7 100644
--- a/app/routes/circulars.$circularId/route.tsx
+++ b/app/routes/circulars.$circularId/route.tsx
@@ -11,8 +11,8 @@ import { Link, useLoaderData } from '@remix-run/react'
 import { Button, ButtonGroup, Icon } from '@trussworks/react-uswds'
 
 import { get } from '../circulars/circulars.server'
+import { PlainTextBody } from './Body'
 import { FrontMatter } from './FrontMatter'
-import { PlainTextBody } from './PlainTextBody'
 import { origin } from '~/lib/env.server'
 import { getCanonicalUrlHeaders, pickHeaders } from '~/lib/headers.server'
 import { useSearchString } from '~/lib/utils'
@@ -93,7 +93,7 @@ export default function () {
       </ButtonGroup>
       <h1>GCN Circular {circularId}</h1>
       <FrontMatter {...frontMatter} />
-      <PlainTextBody>{body}</PlainTextBody>
+      <PlainTextBody className="margin-y-2">{body}</PlainTextBody>
     </>
   )
 }
diff --git a/app/routes/circulars._archive._index.tsx b/app/routes/circulars._archive._index.tsx
deleted file mode 100644
index e6a615820b..0000000000
--- a/app/routes/circulars._archive._index.tsx
+++ /dev/null
@@ -1,367 +0,0 @@
-/*!
- * Copyright © 2023 United States Government as represented by the
- * Administrator of the National Aeronautics and Space Administration.
- * All Rights Reserved.
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-import type { DataFunctionArgs } from '@remix-run/node'
-import {
-  Form,
-  Link,
-  useActionData,
-  useLoaderData,
-  useSearchParams,
-  useSubmit,
-} from '@remix-run/react'
-import {
-  Button,
-  ButtonGroup,
-  Icon,
-  Label,
-  Select,
-  TextInput,
-} from '@trussworks/react-uswds'
-import classNames from 'classnames'
-import clamp from 'lodash/clamp'
-import { useState } from 'react'
-
-import { circularRedirect, search } from './circulars/circulars.server'
-import type { action } from './circulars/route'
-import Hint from '~/components/Hint'
-import { usePagination } from '~/lib/pagination'
-import { useFeature } from '~/root'
-
-import searchImg from 'nasawds/src/img/usa-icons-bg/search--white.svg'
-
-export async function loader({ request: { url } }: DataFunctionArgs) {
-  const { searchParams } = new URL(url)
-  const query = searchParams.get('query') || undefined
-  if (query) {
-    await circularRedirect(query)
-  }
-  const startDate = searchParams.get('startDate') || undefined
-  const endDate = searchParams.get('endDate') || undefined
-  const page = parseInt(searchParams.get('page') || '1')
-  const limit = clamp(parseInt(searchParams.get('limit') || '100'), 1, 100)
-  const results = await search({
-    query,
-    page: page - 1,
-    limit,
-    startDate,
-    endDate,
-  })
-
-  return { page, ...results }
-}
-
-function getPageLink({
-  page,
-  limit,
-  query,
-  startDate,
-  endDate,
-}: {
-  page: number
-  limit?: number
-  query?: string
-  startDate?: string
-  endDate?: string
-}) {
-  const searchParams = new URLSearchParams()
-  if (page > 1) searchParams.set('page', page.toString())
-  if (limit && limit != 100) searchParams.set('limit', limit.toString())
-  if (query) searchParams.set('query', query)
-  if (startDate) searchParams.set('startDate', startDate)
-  if (endDate) searchParams.set('endDate', endDate)
-
-  const searchString = searchParams.toString()
-  return searchString && `?${searchString}`
-}
-
-function Pagination({
-  page,
-  totalPages,
-  ...queryStringProps
-}: {
-  page: number
-  totalPages: number
-  limit?: number
-  query?: string
-  startDate?: string
-  endDate?: string
-}) {
-  const pages = usePagination({ currentPage: page, totalPages })
-
-  return (
-    <nav aria-label="Pagination" className="usa-pagination">
-      <ul className="usa-pagination__list">
-        {pages.map((pageProps, i) => {
-          switch (pageProps.type) {
-            case 'prev':
-              return (
-                <li
-                  className="usa-pagination__item usa-pagination__arrow"
-                  key={i}
-                >
-                  <Link
-                    to={getPageLink({
-                      page: pageProps.number,
-                      ...queryStringProps,
-                    })}
-                    className="usa-pagination__link usa-pagination__previous-page"
-                    aria-label="Previous page"
-                  >
-                    <Icon.NavigateBefore role="presentation" />
-                    <span className="usa-pagination__link-text">Previous</span>
-                  </Link>
-                </li>
-              )
-            case 'overflow':
-              return (
-                <li
-                  className="usa-pagination__item usa-pagination__overflow"
-                  role="presentation"
-                  key={i}
-                >
-                  <span>…</span>
-                </li>
-              )
-            case 'next':
-              return (
-                <li
-                  className="usa-pagination__item usa-pagination__arrow"
-                  key={i}
-                >
-                  <Link
-                    to={getPageLink({
-                      page: pageProps.number,
-                      ...queryStringProps,
-                    })}
-                    className="usa-pagination__link usa-pagination__next-page"
-                    aria-label="Next page"
-                  >
-                    <Icon.NavigateNext role="presentation" />
-                    <span className="usa-pagination__link-text">Next</span>
-                  </Link>
-                </li>
-              )
-            default:
-              return (
-                <li
-                  className="usa-pagination__item usa-pagination__page-no"
-                  key={i}
-                >
-                  <Link
-                    to={getPageLink({
-                      page: pageProps.number,
-                      ...queryStringProps,
-                    })}
-                    className={classNames('usa-pagination__button', {
-                      'usa-current': pageProps.isCurrent,
-                    })}
-                    prefetch="render"
-                    aria-label={`Page ${pageProps.number}`}
-                    aria-current={pageProps.isCurrent}
-                  >
-                    {pageProps.number}
-                  </Link>
-                </li>
-              )
-          }
-        })}
-      </ul>
-    </nav>
-  )
-}
-
-const dateSelectorLabels: Record<string, string> = {
-  hour: 'Last hour',
-  day: 'Last day',
-  week: 'Last week',
-  month: 'Last month',
-  year: 'Last year',
-  today: 'Today',
-  mtd: 'Month to date',
-  ytd: 'Year to date',
-}
-
-function DateSelectorButton({
-  startDate,
-  endDate,
-  expanded,
-  ...props
-}: {
-  startDate?: string
-  endDate?: string
-  expanded?: boolean
-} & Omit<Parameters<typeof ButtonGroup>[0], 'segmented' | 'children'>) {
-  const slimClasses = 'height-4 padding-y-0'
-
-  return (
-    <ButtonGroup type="segmented" {...props}>
-      <Button type="button" className={`${slimClasses} padding-x-2`}>
-        {(startDate && dateSelectorLabels[startDate]) ||
-          (startDate && endDate && (
-            <>
-              {startDate}—{endDate}
-            </>
-          )) ||
-          'Filter by date'}
-      </Button>
-      <Button type="button" className={`${slimClasses} padding-x-1`}>
-        <Icon.CalendarToday role="presentation" />
-        {expanded ? (
-          <Icon.ExpandLess role="presentation" />
-        ) : (
-          <Icon.ExpandMore role="presentation" />
-        )}
-      </Button>
-    </ButtonGroup>
-  )
-}
-
-export default function () {
-  const newItem = useActionData<typeof action>()
-  const { items, page, totalPages, totalItems } = useLoaderData<typeof loader>()
-  const featureCircularsFilterByDate = useFeature('CIRCULARS_FILTER_BY_DATE')
-
-  // Concatenate items from the action and loader functions
-  const allItems = [...(newItem ? [newItem] : []), ...(items || [])]
-
-  const [searchParams] = useSearchParams()
-  const limit = searchParams.get('limit') || '100'
-  const query = searchParams.get('query') || undefined
-  const startDate = searchParams.get('startDate') || undefined
-  const endDate = searchParams.get('endDate') || undefined
-
-  let searchString = searchParams.toString()
-  if (searchString) searchString = `?${searchString}`
-
-  const [inputQuery, setInputQuery] = useState(query)
-  const clean = inputQuery === query
-
-  const submit = useSubmit()
-
-  return (
-    <>
-      <h1>GCN Circulars</h1>
-      <p className="usa-paragraph">
-        <b>
-          GCN Circulars are rapid astronomical bulletins submitted by and
-          distributed to community members worldwide.
-        </b>{' '}
-        They are used to share discoveries, observations, quantitative near-term
-        predictions, requests for follow-up observations, or future observing
-        plans related to high-energy, multi-messenger, and variable or transient
-        astrophysical events. See the{' '}
-        <Link className="usa-link" to="/docs/circulars">
-          documentation
-        </Link>{' '}
-        for help with subscribing to or submitting Circulars.
-      </p>
-      <ButtonGroup className="position-sticky top-0 bg-white margin-bottom-1 padding-top-1">
-        <Form
-          className="display-inline-block usa-search usa-search--small"
-          role="search"
-          id="searchForm"
-        >
-          <Label srOnly={true} htmlFor="query">
-            Search
-          </Label>
-          <TextInput
-            autoFocus
-            id="query"
-            name="query"
-            type="search"
-            defaultValue={inputQuery}
-            placeholder="Search"
-            aria-describedby="searchHint"
-            onChange={({ target: { form, value } }) => {
-              setInputQuery(value)
-              if (!value) submit(form)
-            }}
-          />
-          <Button type="submit">
-            <img
-              src={searchImg}
-              className="usa-search__submit-icon"
-              alt="Search"
-            />
-          </Button>
-        </Form>
-        {featureCircularsFilterByDate && (
-          <DateSelectorButton startDate={startDate} endDate={endDate} />
-        )}
-        <Link to={`/circulars/new${searchString}`}>
-          <Button
-            type="button"
-            className="height-4 padding-top-0 padding-bottom-0"
-          >
-            <Icon.Edit role="presentation" /> New
-          </Button>
-        </Link>
-      </ButtonGroup>
-      <Hint id="searchHint">
-        Search for Circulars by submitter, subject, or body text (e.g. 'Fermi
-        GRB'). <br />
-        To navigate to a specific circular, enter the associated Circular ID
-        (e.g. 'gcn123', 'Circular 123', or '123').
-      </Hint>
-      {clean && (
-        <>
-          {query && (
-            <h3>
-              {totalItems} result{totalItems != 1 && 's'} found.
-            </h3>
-          )}
-          <ol>
-            {allItems.map(({ circularId, subject }) => (
-              <li key={circularId} value={circularId}>
-                <Link
-                  className="usa-link"
-                  to={`/circulars/${circularId}${searchString}`}
-                >
-                  {subject}
-                </Link>
-              </li>
-            ))}
-          </ol>
-          <div className="display-flex flex-row flex-wrap">
-            <div className="display-flex flex-align-self-center margin-right-2 width-auto">
-              <div>
-                <Select
-                  id="limit"
-                  className="width-auto height-5 padding-y-0 margin-y-0"
-                  name="limit"
-                  defaultValue="100"
-                  form="searchForm"
-                  onChange={({ target: { form } }) => {
-                    submit(form)
-                  }}
-                >
-                  <option value="10">10 / page</option>
-                  <option value="20">20 / page</option>
-                  <option value="50">50 / page</option>
-                  <option value="100">100 / page</option>
-                </Select>
-              </div>
-            </div>
-            <div className="display-flex flex-fill">
-              {totalPages > 1 && (
-                <Pagination
-                  query={query}
-                  page={page}
-                  limit={parseInt(limit)}
-                  totalPages={totalPages}
-                  startDate={startDate}
-                  endDate={endDate}
-                />
-              )}
-            </div>
-          </div>
-        </>
-      )}
-    </>
-  )
-}
diff --git a/app/routes/circulars._archive._index/CircularPagination.tsx b/app/routes/circulars._archive._index/CircularPagination.tsx
new file mode 100644
index 0000000000..664ed37639
--- /dev/null
+++ b/app/routes/circulars._archive._index/CircularPagination.tsx
@@ -0,0 +1,145 @@
+/*!
+ * Copyright © 2023 United States Government as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import { Link } from '@remix-run/react'
+import { Icon } from '@trussworks/react-uswds'
+import classNames from 'classnames'
+
+import { usePagination } from '~/lib/pagination'
+
+function getPageLink({
+  page,
+  limit,
+  query,
+  startDate,
+  endDate,
+}: {
+  page: number
+  limit?: number
+  query?: string
+  startDate?: string
+  endDate?: string
+}) {
+  const searchParams = new URLSearchParams()
+  if (page > 1) searchParams.set('page', page.toString())
+  if (limit && limit != 100) searchParams.set('limit', limit.toString())
+  if (query) searchParams.set('query', query)
+  if (startDate) searchParams.set('startDate', startDate)
+  if (endDate) searchParams.set('endDate', endDate)
+
+  const searchString = searchParams.toString()
+  return searchString && `?${searchString}`
+}
+
+export default function ({
+  page,
+  totalPages,
+  ...queryStringProps
+}: {
+  page: number
+  totalPages: number
+  limit?: number
+  query?: string
+  startDate?: string
+  endDate?: string
+}) {
+  const pages = usePagination({ currentPage: page, totalPages })
+  return (
+    <nav aria-label="Pagination" className="usa-pagination">
+      <ul className="usa-pagination__list">
+        {pages.map((pageProps, i) => {
+          switch (pageProps.type) {
+            case 'prev':
+              if (totalPages >= page) {
+                return (
+                  <li
+                    className="usa-pagination__item usa-pagination__arrow"
+                    key={i}
+                  >
+                    <Link
+                      to={getPageLink({
+                        page: pageProps.number,
+                        ...queryStringProps,
+                      })}
+                      className="usa-pagination__link usa-pagination__previous-page"
+                      aria-label="Previous page"
+                    >
+                      <Icon.NavigateBefore role="presentation" />
+                      <span className="usa-pagination__link-text">
+                        Previous
+                      </span>
+                    </Link>
+                  </li>
+                )
+              } else {
+                return null
+              }
+            case 'overflow':
+              if (totalPages >= page) {
+                return (
+                  <li
+                    className="usa-pagination__item usa-pagination__overflow"
+                    role="presentation"
+                    key={i}
+                  >
+                    <span>…</span>
+                  </li>
+                )
+              } else {
+                return null
+              }
+            case 'next':
+              if (totalPages > page) {
+                return (
+                  <li
+                    className="usa-pagination__item usa-pagination__arrow"
+                    key={i}
+                  >
+                    <Link
+                      to={getPageLink({
+                        page: pageProps.number,
+                        ...queryStringProps,
+                      })}
+                      className="usa-pagination__link usa-pagination__next-page"
+                      aria-label="Next page"
+                    >
+                      <Icon.NavigateNext role="presentation" />
+                      <span className="usa-pagination__link-text">Next</span>
+                    </Link>
+                  </li>
+                )
+              } else {
+                return null
+              }
+            default:
+              return (
+                <li
+                  className="usa-pagination__item usa-pagination__page-no"
+                  key={i}
+                >
+                  <Link
+                    to={getPageLink({
+                      page: pageProps.number,
+                      ...queryStringProps,
+                    })}
+                    className={classNames('usa-pagination__button', {
+                      'usa-current': pageProps.isCurrent,
+                    })}
+                    prefetch="render"
+                    aria-label={`Page ${pageProps.number}`}
+                    aria-current={pageProps.isCurrent}
+                  >
+                    {pageProps.number}
+                  </Link>
+                </li>
+              )
+          }
+        })}
+      </ul>
+    </nav>
+  )
+}
diff --git a/app/routes/circulars._archive._index/CircularsHeader.tsx b/app/routes/circulars._archive._index/CircularsHeader.tsx
new file mode 100644
index 0000000000..e3cd277428
--- /dev/null
+++ b/app/routes/circulars._archive._index/CircularsHeader.tsx
@@ -0,0 +1,30 @@
+/*!
+ * Copyright © 2023 United States Government as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import { Link } from '@remix-run/react'
+
+export default function () {
+  return (
+    <>
+      <h1>GCN Circulars</h1>
+      <p className="usa-paragraph">
+        <b>
+          GCN Circulars are rapid astronomical bulletins submitted by and
+          distributed to community members worldwide.
+        </b>{' '}
+        They are used to share discoveries, observations, quantitative near-term
+        predictions, requests for follow-up observations, or future observing
+        plans related to high-energy, multi-messenger, and variable or transient
+        astrophysical events. See the{' '}
+        <Link className="usa-link" to="/docs/circulars">
+          documentation
+        </Link>{' '}
+        for help with subscribing to or submitting Circulars.
+      </p>
+    </>
+  )
+}
diff --git a/app/routes/circulars._archive._index/CircularsIndex.tsx b/app/routes/circulars._archive._index/CircularsIndex.tsx
new file mode 100644
index 0000000000..99a2cf8f5a
--- /dev/null
+++ b/app/routes/circulars._archive._index/CircularsIndex.tsx
@@ -0,0 +1,44 @@
+/*!
+ * Copyright © 2023 United States Government as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import { Link } from '@remix-run/react'
+
+import type { CircularMetadata } from '../circulars/circulars.lib'
+
+export default function ({
+  allItems,
+  searchString,
+  totalItems,
+  query,
+}: {
+  allItems: CircularMetadata[]
+  searchString: string
+  totalItems: number
+  query?: string
+}) {
+  return (
+    <>
+      {query && (
+        <h3>
+          {totalItems} result{totalItems != 1 && 's'} found.
+        </h3>
+      )}
+      <ol>
+        {allItems.map(({ circularId, subject }) => (
+          <li key={circularId} value={circularId}>
+            <Link
+              className="usa-link"
+              to={`/circulars/${circularId}${searchString}`}
+            >
+              {subject}
+            </Link>
+          </li>
+        ))}
+      </ol>
+    </>
+  )
+}
diff --git a/app/routes/circulars._archive._index/DateSelectorButton.tsx b/app/routes/circulars._archive._index/DateSelectorButton.tsx
new file mode 100644
index 0000000000..1335f1848e
--- /dev/null
+++ b/app/routes/circulars._archive._index/DateSelectorButton.tsx
@@ -0,0 +1,55 @@
+/*!
+ * Copyright © 2023 United States Government as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import { Button, ButtonGroup, Icon } from '@trussworks/react-uswds'
+
+const dateSelectorLabels: Record<string, string> = {
+  hour: 'Last Hour',
+  today: 'Today',
+  day: 'Last Day',
+  week: 'Last Week',
+  month: 'Last Month',
+  year: 'Last Year',
+  ytd: 'Year to Date',
+}
+
+export default function ({
+  startDate,
+  endDate,
+  expanded,
+  ...props
+}: {
+  startDate?: string
+  endDate?: string
+  expanded?: boolean
+} & Omit<Parameters<typeof ButtonGroup>[0], 'segmented' | 'children'>) {
+  const slimClasses = 'height-4 padding-y-0'
+
+  return (
+    <ButtonGroup type="segmented" {...props}>
+      <Button type="button" className={`${slimClasses} padding-x-2`}>
+        {(startDate && dateSelectorLabels[startDate]) ||
+          (startDate && endDate && (
+            <>
+              {startDate}—{endDate}
+            </>
+          )) ||
+          (startDate && <>After {startDate}</>) ||
+          (endDate && <>Before {endDate}</>) ||
+          'Filter by date'}
+      </Button>
+      <Button type="button" className={`${slimClasses} padding-x-1`}>
+        <Icon.CalendarToday role="presentation" />
+        {expanded ? (
+          <Icon.ExpandLess role="presentation" />
+        ) : (
+          <Icon.ExpandMore role="presentation" />
+        )}
+      </Button>
+    </ButtonGroup>
+  )
+}
diff --git a/app/routes/circulars._archive._index/route.tsx b/app/routes/circulars._archive._index/route.tsx
new file mode 100644
index 0000000000..58e7d8fffa
--- /dev/null
+++ b/app/routes/circulars._archive._index/route.tsx
@@ -0,0 +1,311 @@
+/*!
+ * Copyright © 2023 United States Government as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All Rights Reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import type { DataFunctionArgs } from '@remix-run/node'
+import {
+  Form,
+  Link,
+  useActionData,
+  useLoaderData,
+  useSearchParams,
+  useSubmit,
+} from '@remix-run/react'
+import {
+  Button,
+  ButtonGroup,
+  CardBody,
+  CardFooter,
+  DateRangePicker,
+  Grid,
+  Icon,
+  Label,
+  Radio,
+  Select,
+  TextInput,
+} from '@trussworks/react-uswds'
+import clamp from 'lodash/clamp'
+import { useState } from 'react'
+
+import { circularRedirect, search } from '../circulars/circulars.server'
+import type { action } from '../circulars/route'
+import CircularPagination from './CircularPagination'
+import CircularsHeader from './CircularsHeader'
+import CircularsIndex from './CircularsIndex'
+import DateSelectorButton from './DateSelectorButton'
+import DetailsDropdownContent from '~/components/DetailsDropdownContent'
+import Hint from '~/components/Hint'
+import { useFeature } from '~/root'
+
+import searchImg from 'nasawds/src/img/usa-icons-bg/search--white.svg'
+
+export async function loader({ request: { url } }: DataFunctionArgs) {
+  const { searchParams } = new URL(url)
+  const query = searchParams.get('query') || undefined
+  if (query) {
+    await circularRedirect(query)
+  }
+  const startDate = searchParams.get('startDate') || undefined
+  const endDate = searchParams.get('endDate') || undefined
+  const page = parseInt(searchParams.get('page') || '1')
+  const limit = clamp(parseInt(searchParams.get('limit') || '100'), 1, 100)
+  const results = await search({
+    query,
+    page: page - 1,
+    limit,
+    startDate,
+    endDate,
+  })
+
+  return { page, ...results }
+}
+
+export default function () {
+  const newItem = useActionData<typeof action>()
+  const { items, page, totalPages, totalItems } = useLoaderData<typeof loader>()
+  const featureCircularsFilterByDate = useFeature('CIRCULARS_FILTER_BY_DATE')
+
+  // Concatenate items from the action and loader functions
+  const allItems = [...(newItem ? [newItem] : []), ...(items || [])]
+
+  const [searchParams] = useSearchParams()
+  const limit = searchParams.get('limit') || '100'
+  const query = searchParams.get('query') || undefined
+  const startDate = searchParams.get('startDate') || undefined
+  const endDate = searchParams.get('endDate') || undefined
+
+  let searchString = searchParams.toString()
+  if (searchString) searchString = `?${searchString}`
+
+  const [inputQuery, setInputQuery] = useState(query)
+  const [inputDateGte, setInputDateGte] = useState(startDate)
+  const [inputDateLte, setInputDateLte] = useState(endDate)
+  const [showContent, setShowContent] = useState(false)
+  const [showDateRange, setShowDateRange] = useState(false)
+  const clean = inputQuery === query
+
+  const submit = useSubmit()
+
+  function setFuzzyTime(startDate?: string) {
+    setShowDateRange(false)
+    setInputDateGte(startDate)
+    setInputDateLte('')
+  }
+
+  function setDateRange() {
+    setShowContent(false)
+    if (inputDateGte) searchParams.set('startDate', inputDateGte)
+    else searchParams.delete('startDate')
+    if (inputDateLte) searchParams.set('endDate', inputDateLte)
+    else searchParams.delete('endDate')
+    submit(searchParams, {
+      method: 'get',
+      action: '/circulars',
+    })
+  }
+
+  const dateSelectorLabels: Record<string, string> = {
+    hour: 'Last Hour',
+    today: 'Today',
+    day: 'Last Day',
+    week: 'Last Week',
+    month: 'Last Month',
+    year: 'Last Year',
+    ytd: 'Year to Date',
+  }
+
+  return (
+    <>
+      <CircularsHeader />
+      <ButtonGroup className="position-sticky top-0 bg-white margin-bottom-1 padding-top-1 z-top">
+        <Form
+          className="display-inline-block usa-search usa-search--small"
+          role="search"
+          id="searchForm"
+        >
+          <Label srOnly={true} htmlFor="query">
+            Search
+          </Label>
+          <TextInput
+            autoFocus
+            id="query"
+            name="query"
+            type="search"
+            defaultValue={inputQuery}
+            placeholder="Search"
+            aria-describedby="searchHint"
+            onChange={({ target: { form, value } }) => {
+              setInputQuery(value)
+              if (!value) submit(form)
+            }}
+          />
+          <Button type="submit">
+            <img
+              src={searchImg}
+              className="usa-search__submit-icon"
+              alt="Search"
+            />
+          </Button>
+        </Form>
+        {featureCircularsFilterByDate && (
+          <>
+            <DateSelectorButton
+              startDate={startDate}
+              endDate={endDate}
+              onClick={() => {
+                setShowContent((shown) => !shown)
+                setShowDateRange(false)
+              }}
+              expanded={showContent}
+            />
+            {showContent && (
+              <DetailsDropdownContent className="maxw-card-xlg">
+                <CardBody>
+                  <Grid row>
+                    <Grid col={4} key={`radio-alltime`}>
+                      <Radio
+                        id={`radio-alltime`}
+                        name="radio-date"
+                        value=""
+                        label="All Time"
+                        defaultChecked={true}
+                        onChange={(e) => {
+                          setInputDateGte(e.target.value)
+                        }}
+                      />
+                    </Grid>
+                    {Object.entries(dateSelectorLabels).map(
+                      ([value, label]) => (
+                        <Grid col={4} key={`radio-${value}`}>
+                          <Radio
+                            id={`radio-${value}`}
+                            name="radio-date"
+                            value={value}
+                            label={label}
+                            checked={value === inputDateGte}
+                            onChange={() => {
+                              setFuzzyTime(value)
+                            }}
+                          />
+                        </Grid>
+                      )
+                    )}
+                    <Grid col={4}>
+                      <Radio
+                        id="radio-custom"
+                        name="radio-date"
+                        value="custom"
+                        label="Custom Range..."
+                        checked={showDateRange}
+                        onChange={(e) => {
+                          setShowDateRange(e.target.checked)
+                        }}
+                      />
+                    </Grid>
+                  </Grid>
+                  {showDateRange && (
+                    <DateRangePicker
+                      startDateHint="dd/mm/yyyy"
+                      startDateLabel="Start Date"
+                      className="margin-bottom-2"
+                      startDatePickerProps={{
+                        id: 'event-date-start',
+                        name: 'event-date-start',
+                        defaultValue: 'startDate',
+                        onChange: (value) => {
+                          setInputDateGte(value)
+                        },
+                      }}
+                      endDateHint="dd/mm/yyyy"
+                      endDateLabel="End Date"
+                      endDatePickerProps={{
+                        id: 'event-date-end',
+                        name: 'event-date-end',
+                        defaultValue: 'endDate',
+                        onChange: (value) => {
+                          setInputDateLte(value)
+                        },
+                      }}
+                    />
+                  )}
+
+                  <CardFooter>
+                    <Button
+                      type="button"
+                      form="searchForm"
+                      onClick={() => {
+                        setDateRange()
+                      }}
+                    >
+                      <Icon.CalendarToday /> Submit
+                    </Button>
+                  </CardFooter>
+                </CardBody>
+              </DetailsDropdownContent>
+            )}
+          </>
+        )}
+        <Link to={`/circulars/new${searchString}`}>
+          <Button
+            type="button"
+            className="height-4 padding-top-0 padding-bottom-0"
+          >
+            <Icon.Edit role="presentation" /> New
+          </Button>
+        </Link>
+      </ButtonGroup>
+      <Hint id="searchHint">
+        Search for Circulars by submitter, subject, or body text (e.g. 'Fermi
+        GRB'). <br />
+        To navigate to a specific circular, enter the associated Circular ID
+        (e.g. 'gcn123', 'Circular 123', or '123').
+      </Hint>
+      {clean && (
+        <>
+          <CircularsIndex
+            allItems={allItems}
+            searchString={searchString}
+            totalItems={totalItems}
+            query={query}
+          />
+          <div className="display-flex flex-row flex-wrap">
+            <div className="display-flex flex-align-self-center margin-right-2 width-auto">
+              <div>
+                <Select
+                  id="limit"
+                  className="width-auto height-5 padding-y-0 margin-y-0"
+                  name="limit"
+                  defaultValue="100"
+                  form="searchForm"
+                  onChange={({ target: { form } }) => {
+                    submit(form)
+                  }}
+                >
+                  <option value="10">10 / page</option>
+                  <option value="20">20 / page</option>
+                  <option value="50">50 / page</option>
+                  <option value="100">100 / page</option>
+                </Select>
+              </div>
+            </div>
+            <div className="display-flex flex-fill">
+              {totalPages > 1 && (
+                <CircularPagination
+                  query={query}
+                  page={page}
+                  limit={parseInt(limit)}
+                  totalPages={totalPages}
+                  startDate={startDate}
+                  endDate={endDate}
+                />
+              )}
+            </div>
+          </div>
+        </>
+      )}
+    </>
+  )
+}
diff --git a/app/routes/circulars.new.tsx b/app/routes/circulars.new.tsx
index 463a1c851e..cb27f47bbc 100644
--- a/app/routes/circulars.new.tsx
+++ b/app/routes/circulars.new.tsx
@@ -23,14 +23,17 @@ import {
   Modal,
   ModalFooter,
   ModalHeading,
+  Table,
   TextInput,
   Textarea,
 } from '@trussworks/react-uswds'
 import classnames from 'classnames'
-import { useState } from 'react'
+import { type ReactNode, useContext, useState } from 'react'
 import { dedent } from 'ts-dedent'
 
 import { getUser } from './_auth/user.server'
+import { AstroDataContext } from './circulars.$circularId/AstroDataContext'
+import { MarkdownBody, PlainTextBody } from './circulars.$circularId/Body'
 import {
   bodyIsValid,
   formatAuthor,
@@ -82,6 +85,46 @@ function useBodyPlaceholder() {
     `)
 }
 
+function ToggleButton<T extends Record<string, ReactNode>>({
+  defaultValue,
+  options,
+  onChange,
+}: {
+  defaultValue: keyof T
+  options: T
+  onChange?: (value: keyof T) => void
+}) {
+  const [value, setValue] = useState(defaultValue)
+
+  return (
+    <ButtonGroup type="segmented">
+      {Object.entries(options).map(([key, label]) => (
+        <Button
+          key={key}
+          type="button"
+          outline={key !== value}
+          onClick={() => {
+            setValue(key)
+            if (onChange && key !== value) onChange(key)
+          }}
+        >
+          {label}
+        </Button>
+      ))}
+    </ButtonGroup>
+  )
+}
+
+function useStateToggle(value: boolean) {
+  const [state, setState] = useState(value)
+
+  function toggle() {
+    setState((state) => !state)
+  }
+
+  return [state, toggle] as const
+}
+
 export default function () {
   const { isAuthenticated, isAuthorized, formattedAuthor } =
     useLoaderData<typeof loader>()
@@ -99,17 +142,16 @@ export default function () {
   const [subjectValid, setSubjectValid] = useState(
     subjectIsValid(defaultSubject)
   )
-  const [bodyValid, setBodyValid] = useState(bodyIsValid(defaultBody))
-  const [showKeywords, setShowKeywords] = useState(false)
+  const [body, setBody] = useState(defaultBody)
+  const bodyValid = bodyIsValid(body)
+  const [showKeywords, toggleShowKeywords] = useStateToggle(false)
+  const [showBodySyntax, toggleShowBodySyntax] = useStateToggle(false)
+  const [showPreview, setShowPreview] = useState(false)
   const sending = Boolean(useNavigation().formData)
   const valid = subjectValid && bodyValid
 
-  function toggleShowKeywords() {
-    setShowKeywords(!showKeywords)
-  }
-
   return (
-    <>
+    <AstroDataContext.Provider value={{ rel: 'noopener', target: '_blank' }}>
       <h1>New GCN Circular</h1>
       <Form method="POST" action={`/circulars${searchString}`}>
         <InputGroup className="border-0 maxw-full">
@@ -169,7 +211,15 @@ export default function () {
         <label hidden htmlFor="body">
           Body
         </label>
+        <ToggleButton
+          defaultValue="edit"
+          options={{ edit: 'Edit', preview: 'Preview' }}
+          onChange={(value) => {
+            setShowPreview(value === 'preview')
+          }}
+        />
         <Textarea
+          hidden={showPreview}
           name="body"
           id="body"
           aria-describedby="bodyDescription"
@@ -180,15 +230,35 @@ export default function () {
             'usa-input--success': bodyValid,
           })}
           onChange={({ target: { value } }) => {
-            setBodyValid(bodyIsValid(value))
+            setBody(value)
           }}
         />
+        {showPreview && (
+          <PlainTextBody className="border padding-1 margin-top-1">
+            {body}
+          </PlainTextBody>
+        )}
         <div className="text-base margin-bottom-1" id="bodyDescription">
           <small>
             Body text. If this is your first Circular, please review the{' '}
-            <Link to="/docs/circulars/styleguide">style guide</Link>.
+            <Link to="/docs/circulars/styleguide">style guide</Link>. References
+            to Circulars, DOIs, arXiv preprints, and transients are
+            automatically shown as links; see{' '}
+            <button
+              type="button"
+              className="usa-banner__button margin-left-0"
+              aria-expanded={showBodySyntax}
+              onClick={toggleShowBodySyntax}
+            >
+              <span className="usa-banner__button-text">syntax.</span>
+            </button>
           </small>
         </div>
+        {showBodySyntax && (
+          <div className="text-base padding-x-2 padding-bottom-2">
+            <SyntaxReference />
+          </div>
+        )}
         <ButtonGroup>
           <Link
             to={`/circulars${searchString}`}
@@ -207,7 +277,7 @@ export default function () {
         </ButtonGroup>
       </Form>
       {isAuthorized || <ModalUnauthorized isAuthenticated={isAuthenticated} />}
-    </>
+    </AstroDataContext.Provider>
   )
 }
 
@@ -219,6 +289,75 @@ function PeerEndorsementButton() {
   )
 }
 
+function SyntaxExample({
+  label,
+  children,
+  href,
+  ...props
+}: {
+  label: ReactNode
+  children: string
+} & Pick<JSX.IntrinsicElements['a'], 'href' | 'rel'>) {
+  const { target, rel } = useContext(AstroDataContext)
+  return (
+    <tr>
+      <td>
+        {href ? (
+          <a href={href} {...props} target={target} rel={rel}>
+            {label}
+          </a>
+        ) : (
+          label
+        )}
+      </td>
+      <td>
+        <code>{children}</code>
+      </td>
+      <td>
+        <MarkdownBody>{children}</MarkdownBody>
+      </td>
+    </tr>
+  )
+}
+
+function SyntaxReference() {
+  return (
+    <>
+      <h3>GCN Circulars cross-reference syntax</h3>
+      <Table compact bordered>
+        <thead>
+          <tr>
+            <th>Service</th>
+            <th>Example</th>
+            <th>Output</th>
+          </tr>
+        </thead>
+        <tbody>
+          <SyntaxExample label="GCN Circulars" href="/circulars">
+            GCN 34653, 34660, and 34677
+          </SyntaxExample>
+          <SyntaxExample label="DOI" href="https://www.doi.org" rel="external">
+            doi:10.1103/PhysRevLett.116.061102
+          </SyntaxExample>
+          <SyntaxExample label="arXiv" href="https://arxiv.org" rel="external">
+            arXiv:1602.03837
+          </SyntaxExample>
+          <SyntaxExample
+            label="TNS"
+            href="https://www.wis-tns.org"
+            rel="external"
+          >
+            AT2017gfo
+          </SyntaxExample>
+          <SyntaxExample label="Web address">
+            https://www.swift.psu.edu
+          </SyntaxExample>
+        </tbody>
+      </Table>
+    </>
+  )
+}
+
 function SignInButton() {
   const url = useUrl()
   return (
diff --git a/app/routes/docs.notices.producers.mdx b/app/routes/docs.notices.producers.mdx
index f229c01478..4c72fe9774 100644
--- a/app/routes/docs.notices.producers.mdx
+++ b/app/routes/docs.notices.producers.mdx
@@ -23,10 +23,10 @@ also happy to work with the mission teams to help construct your alerts.
 <ProcessList>
    <ProcessListItem>
      <ProcessListHeading type="h3">
-       Sign in / Sign up 
+       Sign in / Sign up
      </ProcessListHeading>
-     Decide which of your team members will have programmatic access to produce your alerts. 
-     Make sure that they have all signed in at least once to the [GCN website](https://gcn.nasa.gov/login) 
+     Decide which of your team members will have programmatic access to produce your alerts.
+     Make sure that they have all signed in at least once to the [GCN website](https://gcn.nasa.gov/login)
      and the [GCN test website](https://test.gcn.nasa.gov/login).
    </ProcessListItem>
    <ProcessListItem>
@@ -92,6 +92,6 @@ or by sending text to the [GCN Team](https://heasarc.gsfc.nasa.gov/cgi-bin/Feedb
       </ProcessListHeading>
       Work with the
       [GCN Team](/contact)
-      to draft a community announcement, which the GCN Team will circulate. 
+      to draft a community announcement, which the GCN Team will circulate.
    </ProcessListItem>
 </ProcessList>
diff --git a/app/routes/missions.icecube/route.mdx b/app/routes/missions.icecube/route.mdx
index ea5bbddd7e..05a661e621 100644
--- a/app/routes/missions.icecube/route.mdx
+++ b/app/routes/missions.icecube/route.mdx
@@ -48,7 +48,7 @@ The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.e
 IceCube has been sending alerts generated by realtime on astrophysical neutrino searches[^1] [^2]
 over the GCN classic system through the
 [Astrophysical Multimessenger Observatory Network (AMON)](https://www.amon.psu.edu). Work is underway
-to update and transition these to the new GCN Kafka system.  
+to update and transition these to the new GCN Kafka system.
 [Detailed Descriptions and Examples are available.](https://gcn.gsfc.nasa.gov/amon.html)
 
 <div className="overflow-table">
diff --git a/app/routes/user.endorsements/endorsements.server.ts b/app/routes/user.endorsements/endorsements.server.ts
index 910bf47308..0c23aa9fbd 100644
--- a/app/routes/user.endorsements/endorsements.server.ts
+++ b/app/routes/user.endorsements/endorsements.server.ts
@@ -29,7 +29,7 @@ import { origin } from '~/lib/env.server'
 const fromName = 'GCN Endorsements'
 // Call-to-action
 const endorsementsCTA = `
-      
+
 View your pending endorsements here: ${origin}/user/endorsements`
 
 // models
@@ -143,8 +143,8 @@ export class EndorsementsServer {
       subject: 'GCN Peer Endorsements: New Request',
       body: dedent`You have a new peer endorsement request for NASA's General Coordinates Network (GCN) from ${
         this.#currentUserEmail
-      }. 
-      
+      }.
+
       ${note && `Comments from the user: ${note}`}
 
       Approval of an endorsement means that the requestor, ${
@@ -154,7 +154,7 @@ export class EndorsementsServer {
       Please approve this request if you are familiar with the requester, and agree with the criteria. Thank you for your contributions to the GCN community.
 
       If you are not familiar with this user, or believe it to be spam, you may reject or report the endorsement request.
-      
+
       View all of your pending endorsement requests here: ${origin}/user/endorsements`,
     })
   }
@@ -226,7 +226,7 @@ export class EndorsementsServer {
       )
       requestorMessage +=
         `
-      
+
       As an approved user, you may now submit GCN Circulars at ${origin}/circulars/new and be requested for endorsement by other users.` +
         endorsementsCTA
     } else if (status === 'reported')
@@ -256,7 +256,7 @@ export class EndorsementsServer {
         subject: `GCN Peer Endorsements: Endorsement ${status}`,
         body:
           dedent`Your changes to ${requestorEmail}'s peer endorsement request have been processed. They will receive an email as well to confirm the new status.
-        
+
         No further action is required on your part for this user's request.` +
           endorsementsCTA,
       })
diff --git a/app/theme.scss b/app/theme.scss
index 46ee062c94..e05841a8c6 100644
--- a/app/theme.scss
+++ b/app/theme.scss
@@ -31,7 +31,7 @@ h1:first-child {
 }
 
 /*
- * Size and position the NASA meatball logo in the header. 
+ * Size and position the NASA meatball logo in the header.
  */
 
 #site-logo {
@@ -331,8 +331,8 @@ input.react-tags__combobox-input:focus {
 }
 
 /*
- Hero formatting
-*/
+ * Hero formatting
+ */
 
 .gcn-hero-background {
   background-image: none;
@@ -374,24 +374,24 @@ input.react-tags__combobox-input:focus {
 }
 
 /*
-  General Responsiveness in missions page
-*/
+ * General Responsiveness in missions page
+ */
 
 .overflow-table {
   overflow-x: scroll;
 }
 
-/* 
-  Bottom aligned header rows 
-*/
+/*
+ * Bottom aligned header rows
+ */
 .bottom-aligned {
   display: inline;
   vertical-align: bottom;
 }
 
 /*
-  Fully span the row width for segmented columns
-*/
+ * Fully span the row width for segmented columns
+ */
 .full-width-span {
   flex: 1 1 100%;
 }
diff --git a/package-lock.json b/package-lock.json
index e8254b2e3c..10e63a97a9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -19,7 +19,7 @@
         "@remix-run/css-bundle": "^2.0.1",
         "@remix-run/node": "^2.0.0",
         "@remix-run/react": "^2.0.1",
-        "@trussworks/react-uswds": "^5.4.0",
+        "@trussworks/react-uswds": "^5.1.1",
         "addresscompiler": "^1.0.1",
         "aws-lambda-ses-forwarder": "github:lpsinger/aws-lambda-ses-forwarder#aws-sdk-v3",
         "classnames": "^2.3.2",
@@ -74,7 +74,7 @@
         "@nasa-gcn/eslint-config-gitignore": "^0.0.1",
         "@remix-run/dev": "^2.0.1",
         "@remix-run/eslint-config": "^2.0.1",
-        "@testing-library/jest-dom": "^6.1.3",
+        "@testing-library/jest-dom": "^6.1.4",
         "@testing-library/react": "^14.0.0",
         "@trivago/prettier-plugin-sort-imports": "^4.2.0",
         "@types/color-convert": "^2.0.1",
@@ -6599,12 +6599,12 @@
       }
     },
     "node_modules/@testing-library/jest-dom": {
-      "version": "6.1.3",
-      "resolved": "https://registry.npmjs.org/@testing-library/jest-dom/-/jest-dom-6.1.3.tgz",
-      "integrity": "sha512-YzpjRHoCBWPzpPNtg6gnhasqtE/5O4qz8WCwDEaxtfnPO6gkaLrnuXusrGSPyhIGPezr1HM7ZH0CFaUTY9PJEQ==",
+      "version": "6.1.4",
+      "resolved": "https://registry.npmjs.org/@testing-library/jest-dom/-/jest-dom-6.1.4.tgz",
+      "integrity": "sha512-wpoYrCYwSZ5/AxcrjLxJmCU6I5QAJXslEeSiMQqaWmP2Kzpd1LvF/qxmAIW2qposULGWq2gw30GgVNFLSc2Jnw==",
       "dev": true,
       "dependencies": {
-        "@adobe/css-tools": "^4.3.0",
+        "@adobe/css-tools": "^4.3.1",
         "@babel/runtime": "^7.9.2",
         "aria-query": "^5.0.0",
         "chalk": "^3.0.0",
@@ -6782,14 +6782,14 @@
       }
     },
     "node_modules/@trussworks/react-uswds": {
-      "version": "5.4.0",
-      "resolved": "https://registry.npmjs.org/@trussworks/react-uswds/-/react-uswds-5.4.0.tgz",
-      "integrity": "sha512-2cAZ1xg36eCPP0nwsc9NblQYhPb6+KC0IqiEBB5Hwe9B6QyOWqbt2VODKgaqcCTGS7HXbwSpKPznERv+kr9eIA==",
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/@trussworks/react-uswds/-/react-uswds-5.1.1.tgz",
+      "integrity": "sha512-SAlgEIFGCIKyV5aQjIi8dBUwLGdqNkbDHDvXPPWyySlhJkut5MNmZQ73BpFTxke6WqJreljkApPubMWUPiynlw==",
       "engines": {
         "node": ">= 16.20.0"
       },
       "peerDependencies": {
-        "@uswds/uswds": "^3.6.0",
+        "@uswds/uswds": "3.1.0",
         "react": "^16.x || ^17.x || ^18.x",
         "react-dom": "^16.x || ^17.x || ^18.x"
       }
@@ -7405,12 +7405,13 @@
       "dev": true
     },
     "node_modules/@uswds/uswds": {
-      "version": "3.6.1",
-      "resolved": "https://registry.npmjs.org/@uswds/uswds/-/uswds-3.6.1.tgz",
-      "integrity": "sha512-KDr3r4xvbvQ1X05tfacid42m/vLjAAt8N3q2/LDuujjrrBxEdHgK9ROftsesuSBoaD2Fss4lKxS0dPojLzdbbw==",
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/@uswds/uswds/-/uswds-3.1.0.tgz",
+      "integrity": "sha512-6XTeaQD/ipc3x4713mud4Rrr+lRc4nJ1Qw5Oy35dbVEXuKr7DjN4EBoAkbze9OoV0UdmAIvoxolBF/UcpFVKOg==",
       "peer": true,
       "dependencies": {
         "classlist-polyfill": "1.0.3",
+        "domready": "1.0.8",
         "object-assign": "4.1.1",
         "receptor": "1.0.0",
         "resolve-id-refs": "0.1.0"
@@ -9940,6 +9941,12 @@
         "url": "https://github.com/fb55/domhandler?sponsor=1"
       }
     },
+    "node_modules/domready": {
+      "version": "1.0.8",
+      "resolved": "https://registry.npmjs.org/domready/-/domready-1.0.8.tgz",
+      "integrity": "sha512-uIzsOJUNk+AdGE9a6VDeessoMCzF8RrZvJCX/W8QtyfgdR6Uofn/MvRonih3OtCO79b2VDzDOymuiABrQ4z3XA==",
+      "peer": true
+    },
     "node_modules/domutils": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/domutils/-/domutils-3.1.0.tgz",
diff --git a/package.json b/package.json
index 7244587bb9..6ad14d332d 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,7 @@
     "@remix-run/css-bundle": "^2.0.1",
     "@remix-run/node": "^2.0.0",
     "@remix-run/react": "^2.0.1",
-    "@trussworks/react-uswds": "^5.4.0",
+    "@trussworks/react-uswds": "^5.1.1",
     "addresscompiler": "^1.0.1",
     "aws-lambda-ses-forwarder": "github:lpsinger/aws-lambda-ses-forwarder#aws-sdk-v3",
     "classnames": "^2.3.2",
@@ -93,7 +93,7 @@
     "@nasa-gcn/eslint-config-gitignore": "^0.0.1",
     "@remix-run/dev": "^2.0.1",
     "@remix-run/eslint-config": "^2.0.1",
-    "@testing-library/jest-dom": "^6.1.3",
+    "@testing-library/jest-dom": "^6.1.4",
     "@testing-library/react": "^14.0.0",
     "@trivago/prettier-plugin-sort-imports": "^4.2.0",
     "@types/color-convert": "^2.0.1",
diff --git a/remix.config.js b/remix.config.js
index f60e8d2ec7..1a5a02937c 100644
--- a/remix.config.js
+++ b/remix.config.js
@@ -12,7 +12,9 @@ const isProduction = process.env.NODE_ENV === 'production'
 const esmOnlyModules = [
   '@nasa-gcn/remark-rehype-astro',
   'bail',
+  'character-entities',
   'comma-separated-tokens',
+  'decode-named-character-reference',
   'escape-string-regexp',
   'github-slugger',
   'is-plain-obj',
diff --git a/src/plugins/lambdaCognitoPermissions.js b/src/plugins/lambdaCognitoPermissions.js
index 16fea50c08..cda1040ac6 100644
--- a/src/plugins/lambdaCognitoPermissions.js
+++ b/src/plugins/lambdaCognitoPermissions.js
@@ -25,6 +25,7 @@ export const deploy = {
             Effect: 'Allow',
             Action: [
               'cognito-idp:AdminAddUserToGroup',
+              'cognito-idp:AdminGetUser',
               'cognito-idp:AdminListGroupsForUser',
               'cognito-idp:CreateUserPoolClient',
               'cognito-idp:DeleteUserPoolClient',