Work in progress.
What do I have to do to join the GCN system? ...to get notified of GRB?
Go see the Open Invitation page.
Why did my Socket-method packet arrive at T+10sec when I was lead to believe that the GCN-system response time was 3.5-5.5 seconds?
explain the trig-to-enough (searching for enough initial counts) scanning. it looks for up to 10 sec after the trigger to find a 1-sec interval with enough source-counts above background to be able to make a meaningful calculation/solution.
the above was in the BATSE days. now we are in the Swift days; the delay interval can be as short as 7+1sec out to as long as 35+1 sec. with the typcical being 14or21+1 sec.
Why didn't I get a notice for GRB NNNNNN?
mention the various filters and how they reject certain notices to a given site. mention the source dis/enable flags/filters. also mention that one occaisions (rare occaisions) i have been know to make a mistake in the filtering coding or a mistake in the site's configuation (that is why it is important for them to check their configurations closely).
Why is there a newline character at the end of a Socket-method packet?
mention the original socket site had a firewall machine that required it... and it just stayed as part of the formal format after it was no longer necessary because it was too much trouble to change the format.
Why does it go for long stretches (many days) with continous operations and then in a short amount of time 1-3 hours, there are many restarts?
cause i'm installing (and testing) a new version. one restart would be enough if the new feature worked properly, but since it often doesn't, I have to restart. I do pre-install testing, but some of the last little bits require the real system. Also, I try to do the restarts during TM drop-outs or HV_off sessions because there can't be any triggers during these periods -- so nothing is lost.
the above was true in the early years of GCN. now the number of restarts due to new code has dropped a lot. now maybe a couple times a year there will be a 1-hour interval where i restart the program 2or3 times.
What does MAXBC stand for?
OLD BATSE THING: This is an acronym for the "MAXimum Burst Channels". The BATSE on-board flight software monitors the rates in the 8 LADs in the C1 DISCLA channel and the C2 & C3 DISCLA channels (C2 & C3 are the "burst channels") for up to 10 minutes after a trigger looking for and recording the maximum (peak) values. After the 10 minutes, these 16 rates are telemetered to the ground. GCN uses them to produce the MAXBC GRB locations.
What are the 16 numbers at the end of the MAXBC Notice?
Those are the peak count rates in a 64-msec interval for the 8 LADs in the lower C1 channel and the "burst channels".
Why does the MAXBC Intensity differ from the Original Notice Intensity?
OLD BATSE THING: Can be higher (because of the 64msec vs 1024msec sampling of the rates) and it can be lower because the Original Notice can be from two 1-sec samples instead of the normalized single 1-sec sample scale. And of course the Final Notices integrate the light curve up for 2-32 sec after the initial trigger, so they list a "fluence" instead of an "intensity".
Why does the Trigger_type Identification sometimes change between the type listed in the Original Notice and the Final Notice?
OLD BATSE THING: The algorithm used int he program to determine the trigger makes tests in a 5-dimensional phase space using the count rates available at the time of each notice. The counts rates (actually integrated fluences) are different for the Original and Final Notices, so the result of the tests can be different. The algorith is about 98% accurate so it will be wrong 2% of the time.
Why are the roundtrip travel times for GRB packets longer than those for the Imalive packets?
It is not real -- they have the same intrinsic travel times, it's just that the program is forced (due to minimizing the delay times for the e-mail recipients) to measure the times differently.
Where can I get the T90 times for bursts?
In the "Cmnt" column of the "Recent Triggers web page".
What is the purpose of the Test Notices?
Sites can exercise their systems/instruments (an end-to-end test). Their ops programs can treat these Test Notices exactly like real GRB notices (but they always have a type ID that is distinguishable from the real notices and the locations and times are knowable).
What is the deal with different RA,Dec Epochs used the various pager formats?
Pager: The RA,Dec are Current epoch. Short Pager: Epoch 1950. Subject-only: Current Epoch. SubjHHMM-only: J2000 Epoch. These are the 4 "pager" formats. Unlike the full-email which has lots of space (character count) to display all 3 epochs, the pager formats are designed to fit limited char counts. And there are 4 different pager formats because people use different service providers that have different char-cnt limitations. And as each new pager format was added (per specific new GCN client), it was made with the epoch that first-client wanted. At the time, I thought about making the epoch a client-by-client selection (ie another column in the sites.cfg file), but that tripled the amount of scrtach-files and (some factor of processing, and some factor of coding, and some factor of testing), so I decided not to impliment that particular flexibility. Now, it is pretty mcuh cast in concrete
Why does the e-mail come from a person called "vxw"?
The custom front-end computers that process the raw telemetry stream are programmed using the VxWorks Inc. software development product. To use this product within the PACOR division, it was necessary to create a psuedo-person account under the name of "vxw". The programs must also be run under this account, hense all the e-mail comes from this "vxw" account. As an attempt to let people know "who" this e-mail is actually from, we added the string "(BACODINE)" to the Fullname field in the "vxw" entry in the /etc/passwd file. we have
BACODINE is an odd sounding name; how did it come about?
Yes, BACODINE does have a sort of pharmaceutical sound to it. I was being pressed to give the project a name so that it could be written up in some monthly status reports. When I listed the words "BATSE", "coordinates", "distribution", and then "network"; I realized that BCDN could not be pronounced because it had no vowels. So then I started out by doubling up the letters from BATSE, but that still was not pronouncable. Then came a doubling from coordinates, and then it immediately leaped to using the first two letters from the four words that had some relation to what was actually going on in the project. I realize that this is not the standard acronymn convention, but I don' think that is important. ;-)