1. VOE, CalTech, 13Apr05 GCN (GRB Coordinates Network) GRB Event Reporting Scott Barthelmy NASA-GSFC

2. VOE, CalTech, 13Apr05 Table of Contents Description of the GCN System: –Notices and Circulars General Principles of Design & Operation How it collects the information How it distributes the information Future Developments

3. VOE, CalTech, 13Apr05 Description of the System GCN is a system of programs with 2 basic activities: –NOTICES: Collect GRB locations from various s/c and distribute them to interested parties. –CIRCULARS: Collect reports from burst follow-up observers & distribute them to the GRB community. (Easy, Cheap, and Fast) –Delivers data to the various instrument teams These 2 compliment each other –Notices for the real-time observation needs. –Circulars for the humans-in-the-loop after-the-observations.

4. VOE, CalTech, 13Apr05 General Principles of Design & Operation Keep it simple so they need to know as little as possible. Do all the work, so the end-user does none/little. Give them what they want -- the customer is always right. –Give them more than what they want; they will find a way. Know what they want before they want it. –It helps a lot to be a person-in-the-field. Simple data products and formats Simple software for the end-user Simple web pages -- just text, a few plots, a few tables.

5. VOE, CalTech, 13Apr05 How GCN Collects Inputs Interface Programs: –Sockets: integral_ibas_receiver & swift_tdrss_receiver –Email: procmail deposits in import dir gromain periodic checks –Cmd_Files: manually force Test Notices (also param changes) gromain (GCN) swift_tdrss_receiver integral_ibas_receiver ~/import/ ws_sim ws (gsfc) ~/import/ ibas (Europe) gnd proc s/w Items in grey are representative of other missions. HETE_ops (MIT) the world

6. VOE, CalTech, 13Apr05 All Encompassing GCN collects all the information on GRB locations from all the various sources into a single point, and It transmits that information to all the various sites that want that type. Each site need only develop & maintain one connection for all their GRB needs. one-stop shopping

7. VOE, CalTech, 13Apr05 All Automatic, so it is fast All of this collection & distribution of GRB information is done automatically. There are no humans involved (within the GCN system proper), So there is minimal delay (<0.1 sec for HETE, INTEGRAL, and Swift) And only a 1-15 sec delay after receipt of the information from the other sources (e.g. IPN & RXTE) science at the speed of light

8. VOE, CalTech, 13Apr05 Distribution Methods Internet Socket (for the robotic instruments) –0.01-2.0 sec one-way travel time (~0.3 sec 98-percentile) –Imalive packets every 60 sec keep the connection current and it allows both ends to monitor the connection for problems. –Each end can re-initiate the connection if there was a read or write problem. –Each end can break/make the connection at will; there are re-try loops. –Software provided (socket_demo.c from the web site). E-mail (for the human-based operations) –0.1-1 minutes –Format is a combination of both human-readable and machine-parsable. Pagers & Cell-phones (when youre away from operations) –Uses e-mail –Multiple formats for the various service providers: long, short & subject-only. –You can get beeped by the Universe. Web site (pull technology) –Archive all the Notices & Circulars, LightCurves, Images, Spectra, etc.

9. VOE, CalTech, 13Apr05 Socket Packet Contents 160 bytes, 40 dwords Type number Serial number Packet Time RA, Dec, Error Intensity Trigger_ID Flags Misc Flags Plus other type-specific items (box shape, URL, etc) Nearly the same content, and the same format across all types.

10. VOE, CalTech, 13Apr05 Email & Pager Format Examples TITLE: GCN/SWIFT NOTICE NOTICE_DATE: Sat 04 Sep 04 19:42:25 UT NOTICE_TYPE: Swift-BAT GRB Position TRIGGER_NUM: 100002, Seg_Num: 0 GRB_RA: 68.95d {+04h 35m 47s} (J2000), 68.99d {+04h 35m 57s} (current), 68.50d {+04h 34m 01s} (1950) GRB_DEC: -37.30d {-37d 18' 13"} (J2000), -37.29d {-37d 17' 39"} (current), -37.40d {-37d 24' 16"} (1950) GRB_ERROR: 4.00 [arcmin radius, statistical only] GRB_INTEN: 4591 [cnts] Peak=933 [cnts/sec] BKG_INTEN: 6455 [cnts] BKG_TIME: 45384.00 SOD {12:36:24.00} UT GRB_DATE: 13243 TJD; 239 DOY; 04/08/26 GRB_TIME: 45400.44 SOD {12:36:40.44} UT GRB_PHI: 154.14 [deg] GRB_EL: 43.60 [deg] TRIGGER_INDEX: 127 SOLN_STATUS: 3 RATE_SIGNIF: 18.63 [sigma] IMAGE_SIGNIF: 14.79 [sigma] MERIT_PARAMS: +1 +0 +0 +0 +3 +33 +0 +0 +6 +1 SUN_POSTN: 155.52d {+10h 22m 05s} +10.18d {+10d 11' 02"} SUN_DIST: 93.43 [deg] MOON_POSTN: 286.97d {+19h 07m 53s} -27.40d {-27d 23' 53"} MOON_DIST: 106.13 [deg] GAL_COORDS: 239.98,-42.17 [deg] galactic lon,lat of the burst direction ECL_COORDS: 57.00,-58.36 [deg] ecliptic lon,lat of the burst direction COMMENTS: SWIFT-BAT GRB Coordinates. COMMENTS: This is a rate trigger. COMMENTS: A point_source was found. COMMENTS: This does not match any source in the on-board catalog. COMMENTS: This does not match any source in the ground catalog. COMMENTS: This is a GRB. GCN/SWIFT-BAT GRB Position RA=68.988d DEC=-37.295d ERROR=4.0arcmin TIME: 12:36:40.44 UT R_Signif=18.6 I_Signif=14.8 Nearly the same content, and the same format across all types.

11. VOE, CalTech, 13Apr05 Filtering Methods Source Type –Swift, INTEGRAL, HETE, BeppoSAX, IPN, RXTE, ALEXIS, …. –Sub-type selection (instruments, saw/no_saw, etc) Visibility –All, Visible, Nighttime, and Customized Location Uncertainty Size –1 arcsec to 360 deg (match your FOV/tiling capability) Time Delay (time since burst) –1 sec to 40 days Sites get the logical-AND of the 4 filtering conditions Special filtering to accommodate mission-teams There used to be intensity filtering, but multi-missions make that difficult.

12. VOE, CalTech, 13Apr05 Data Products MissionN_InstN_NoticesComment GRO36original ALEXIS11Ex-UV RXTE24GRBs & Trans IPN12Delays HETE231st r-t & small beppoSAX11 INTEGRAL16+1 Swift314+2+5w/Attachments

13. VOE, CalTech, 13Apr05 WEB SITE CONTENTS http://gcn.gsfc.nasa.gov/gcn GRB Notices pages for each S/C (r-t updated) Circulars Archive (r-t updated) Bursts-of-Special Interest (r-t updated) –Circulars grouped by burst Technical Description of the GCN system –All information about the GCN system; all functions, capabilities, formats, protocols, etc.

14. VOE, CalTech, 13Apr05 Sites Configuration for Notices A Notice site is specified by ~60 pieces of information –Site_name, Longitude,Latitude –Dis/enables for each of the ~40 Types –Error_size limit and Time_delay limit –Trigger_ID filtering –Test Notices (5 types) –Distribution method –Attachment format (FITS, GIF, JPEG, Postscript, Text) –Destination address (scott@milkyway.gsfc.nasa.gov or 128.183.16.43:5112)scott@milkyway.gsfc.nasa.gov –Do they want to receive: Socket-disconnect warnings daily socket reports

15. VOE, CalTech, 13Apr05 Persons Configuration for Circulars You must be pre-registered to submit a Circular –6 pieces of information needed: Full NameJohn Doe Institutional affiliation[/project]State University[/Swift] Email login/account name (1)johnd Email domain (1)su.edu Email address you want to receive Circularsjohnd@astro.su.edu Do you want to receive or not (1 or 0)1 –Multiple entries are allowed (ie different logins, machines, institutions, whatever) (1) These two fields used in the vetting check during a submission.

16. VOE, CalTech, 13Apr05 Some GCN Statistics Notices: –460+ "sites" involving ~500 researchers. –sites are: robotic telescopes, human-ops telescopes, pros & amateurs, theorists, people with an interest. Up-time is 99.7% (in the last 2 yr; 98.6% over 13 yr) ~3000 observations on ~600 GRBs Communications Traffic (for 2002): –7000 automated notices/packets were distributed. –600 manual e-mails were received from the "sites" & –500 e-mails were sent back in reply by the GCN operator. Circulars: –860+ recipients –3200+ distributed Both run on a LINUX PC –3 GHz, 512MB RAM, 320 GB disk, Router, and an UPS

17. VOE, CalTech, 13Apr05 Aggressive Campaign for Participation GCN is open to anyone with an interest in GRBs. The Circulars are also open to everyone. Always looking for new sources of GRB locations; looking for other sources.

18. VOE, CalTech, 13Apr05 The Future GLAST (Launch in 2007) AGILE (Launch in 200?) Optical/Radio/X-G Counterpart Notices –Feeds back to the robotic systems what the follow-up people found. MILAGRO events Speech-synthesized phone calls –Dial your phone and TELL you where the burst is.

19. VOE, CalTech, 13Apr05 990123--> GCN--> ROTSE GCN achieved its original design goal; non- observations while still bursting. Combination of real-time data processing & fast-slewing, wide-FOV, automated instruments GCN to ROTSE at T+4sec. ROTSEs 1st observation at T+22sec. mag 11.7, 8.9, 10.0, 11.9, 13.1, 13.8, 14.3 at T+ 22, 47, 73, 157, 281, 447, 612 s. Few x10 54 ergs (2m O c 2 ) Top 0.3% by fluence; top 2% by intensity Z=1.6, halfway to the edge of the Universe C.Akerlof, et al., Nature, 398, Apr99 Since then, there have been Several other simul-detections.

20. VOE, CalTech, 13Apr05 GCN/Swift Data Products Raw (16): –BAT: Alert, Position, No_Position, Lightcurve, Scaled_map –XRT: Position, No_Position, Image, Spectrum, Lightcurve –UVOT: Finding_Chart, Dark_Burst_Image –FOM: Will/Wont_Observe, Will/Wont_Slew –MOC: Initial_Full_Data_Arrival, Updated_Full_Data_Arrival Processed (5): –BAT: Lightcurve –XRT: Image, Spectrum –UVOT: Finding_Chart, Dark_Burst_Image Warning/Error (7): –BAT: Short_Alarm, Long_Alarm –XRT: Emergency –UVOT: Emergency –FOM: PPT_Argument_Error, Safe_Pointing, & Slew_Abort –This is a back-up capability to the primary PSU MOC notification operation.

21. VOE, CalTech, 13Apr05 GRB BASICS Flashes of gamma-rays (0.05 to 1.5 MeV) Random locations; Isotropically distributed Random times; Never repeat Very brief: 0.01 to 100 sec Intense: brighter than the rest of the Universe Cosmological distances: z= 0.1 to 4.5 Sources: HyperNova/Collapsar (for the long), NS/BH mergers (short)