Skip to main content
New! BOOM Notices and Schema v7.0.0. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. 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 documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

19804 results found.

  1. GRB 250714A: SVOM/GRM observation
  2. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  3. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  4. GRB 250713A: Mephisto optical upper limits
  5. GRB 250713A: SVOM/VT optical upper limit
  6. GRB 250713A: NOT optical upper limits
  7. GRB 250713A: OHP/T193 upper limit
  8. GRB 250713A: SVOM/C-GFT upper limit
  9. GRB 250706B/C: 7DT Follow-up Observations
  10. GRB 250713A: EP-FXT counterpart detection
  11. EP250711a: COLIBRÍ continuous optical observations
  12. GRB 250713A: JinShan optical upper limits
  13. GRB 250713A: SVOM detection of a long burst
  14. GRB 250711A: DDOTI Optical Upper Limit
  15. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  16. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  17. GRB 250711A: SVOM/GRM observation
  18. EP250711a: NOT optical counterpart candidate
  19. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  20. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  21. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  22. GRB 250704A: GRANDMA observations
  23. GRB 250704A: SVOM/ECLAIRs refined analysis
  24. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  25. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  26. IceCube-250708A: No Candidates from WINTER
  27. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  28. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  29. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  30. EP250704a/GRB 250704B: 10 GHz VLA detection
  31. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  32. IceCube-250706A: No Candidates from WINTER
  33. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  34. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  35. EP250704a/GRB250704B : HCT optical and NIR upper limits
  36. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  37. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  38. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  39. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  40. GRB 250702F: radio detection with the VLA
  41. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  42. GRB 250706B/C: Fermi-LAT detection
  43. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  44. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  45. GRB 250706B: Swift/UVOT Detection
  46. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 250702F: GRANDMA observations
  48. GRB 250706A: Swift/UVOT Upper Limits
  49. GRB 250706B: REM optical observations
  50. GRB 250706A: REM optical/NIR observations
  51. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  52. IceCube-250416A: DDOTI Optical Upper Limit
  53. IceCube-250706A: COLIBRÍ optical upper limits
  54. GRB 250706A: JinShan optical upper limits
  55. GRB 250706A: SAO RAS optical observations
  56. EP250704A: NOWT Detection
  57. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  58. GRB 250706B: iTelescope optical observations
  59. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  60. GRB 250706B: SVOM/VT optical observation
  61. GRB 250706B: TRT bright optical counterpart detection
  62. GRB 250706A: GROWTH-India Telescope optical upper limit
  63. GRB 250706B: SVOM detection of a long burst
  64. GRB 250706A: Swift detection of a burst
  65. GRB 250704B: Swift-XRT refined Analysis
  66. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  67. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  68. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  69. GRB 250704B: Swift/UVOT Upper Limits
  70. GRB 250704A: Swift/UVOT Detection
  71. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  72. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  73. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  74. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  75. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  76. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  77. GRB 250702F: Kilonova-Catcher optical afterglow detection
  78. GRB 250702F: Monte Agliale Observatory optical observations
  79. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  80. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  81. EP250704a / GRB 250704B: JinShan optical observations
  82. EP250704a / GRB 250704B: SAO RAS optical observations
  83. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  84. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  85. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  86. EP 250704a: BOOTES-5 optical detection
  87. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  88. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  89. GRB 250704A: Swift-XRT afterglow detection
  90. EP250704a / GRB 250704B - REM observations
  91. GRB 250702F: GROWTH-India Telescope optical observations
  92. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  93. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  94. EP250702a: WFST optical observations
  95. EP250704a: COLIBRÍ optical counterpart candidate
  96. EP250704a: Einstein Probe detection of an X-ray transient
  97. GRB 250704A: REM detection of the optical afterglow
  98. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  99. GRB 250704A: SVOM detection of a burst
  100. GRB 250702F: Swift/UVOT Detection

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov