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General Coordinates Network

GCN Circulars are now administered through the General Coordinates Network (effective April 17, 2023)

The modernized GCN Circulars experience is part of the new GCN web site, where you can:

  • Browse and search Circulars in our all-new archive.
  • Sign up for and manage your own email subscriptions.
  • Enroll yourself and your colleagues to submit Circulars with arXiv-style peer endorsements for new contributors.
  • Submit Circulars with our new Web form, or continue to submit by email.

This legacy GCN Classic Circulars service has been disabled.

  • All legacy accounts are transferred to the new system.
  • The legacy archive is frozen.
  • Email submissions to the old address will be forwarded to the new system and processed normally. We encourage use of the new submission address.
For questions, please contact the GCN Team.

GCN Circulars Request


This page allows people to sign up for Circulars within GCN.
(Circulars are prose-style messages submitted by list-members
and are re-distributed to the "GCN Circulars" distribution list.)

There are 7 pieces of information needed to sign-up for the GCN Circulars:
a) Your full name:   John Doe
b) Your institutional and/or project affiliation:   NOAO
c) The email address you want to receive the Circulars:
d) Your email account name you will be using to submit:   jdoe
e) Your domain from which you will be submitting:
f) Your want to receive and submit choices -- * receive and submit, * receive only, * submit only [select a button].
g) Comments: Enter questions or additional information here.

Items d & e may seem like a duplication of item c. Item c can sometimes be different than from where you will be submitting.
Also, some institutions use email servers/forwarders that allow for a generic email address such that
email can be delivered to a person no matter how their true account name/machine moves or changes.
Items d and e are used in the validation process for circular submissions (checks the "From" line w/o the colon in the email header -- see Procedure Step #3).
You can have multiple entries in this Circulars vetting/receiving list.
Item f allows you to have submit-only entries (e.g. say a backup account),
and there can also be more than one receive entry.
For more information on the GCN Circulars.

Items with a red asterisk are required fields.
1)  Enter the 7 pieces of information.
2)  Hit the "Send GCN Circulars request to GCN Admin" button (at bottom of page).
     (This will send me an email (& CC you) with the information you entered, and we will add it to the GCN Circulars vetting/distribution list (and email you it is done).)
3) Optional but encouraged: Send a 1-word test email to so I can check for extra IT Security features in the From-line.

This form has been disabled. See

1) Name*: (Your name, as you want it to appear on outgoing Circulars you submit)
Institution and/or Project Affiliation*: (As you want it to appear on outgoing Circulars you submit)
Receive Address*: (E-mail address to receive Circulars)
Account Name*: (E-mail account name you will be using to submit)
Account Domain*: (Domain you will be using to submit)
Receive*  (select 1 of 3): To Receive & Submit Circulars    Receive-only    Submit-only
Action*  (select 1 of 3): Request a New Entry    Request Check for Existing Entry    Request Update of an Old Entry
Comments/Questions: *
(One sentence about why you are signing up.)


It is useful to send a one-word email to using the account that you just listed above,
so that I can check the actual acctname in the "From "-line in the email header. This acctname@computer.domain can be
different that what you think it is. And this is important because the acctname@computer.domain is the main criteria
in the vetting process when you submit a Circular. The vetting process on a Circular submission depends critcally
on the content of the "From-line" in the email header. (This is the "From "-line that has no colon in it;
as opposed to the "From: "-line with the colon. Anybody can spoof anybody by overwriting the "From: "-line (w/colon),
but it requires root permission to spoof the "From "-line (w/o the colon).) By sending me (not GCN) a short 1-word email,
it allows me to check the kind of "From "-line (w/o colon) you have for your login on that machine. What I see in the
"From "-line will determine if an extra submit-only entry gets added to the vetting list and/or the relaxation flag is set.
There are two causes of these differences -- they are discussed below.

a) NAME SUBSTITUTION: The acctname in the "From "-line in the email header can sometimes be different
than the login acctname, e.g. you log in as "jdoe", but your mail-agent program substitutes "John.Doe" in the From-line
of the outgoing email header. [Currently, only about one in 100 have this modification of the acctname@computer.domain, but it is increasing.]

b) ADDITION OF SECURITY STRING: It is increasingly popular for the IT Security people at your institution to add a string (or two)
to your acctname@computer.domain in the "From "-line of your email. Currently, GCN Circulars processing tests
for an exact match of the acctname and the computer.domain strings to that in your entry(s) in the vetting/distribtution list for the GCN Circulars.
But if your host introduces these extras strings then an exact-match requirement will fail. So I have implimented a flag
to each entry in the vetting/distribtuion list that relaxes that vetting test to only substring-matching.
[Currently, only about one in 200 have this modification of the acctname@computer.domain, but it is increasing.]

This file was last modified on 01-Jan-2020.