Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"

20560 results found.

  1. GRB 250716A: GOTO tentative optical counterpart candidate
  2. Fermi GRB 250716A: Global MASTER-Net observations report
  3. Fermi GRB 250715A: Global MASTER-Net observations report
  4. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  5. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  6. GRB 250713A: Mephisto optical upper limits
  7. Fermi GRB 250714A: Global MASTER-Net observations report
  8. GRB 250713A: NOT optical upper limits
  9. GRB 250713A: OHP/T193 upper limit
  10. GRB 250713A: SVOM/C-GFT upper limit
  11. GRB 250706B/C: 7DT Follow-up Observations
  12. GRB 250713A: Swift-XRT observations
  13. EP250711a: COLIBRÍ continuous optical observations
  14. GRB 250713A: JinShan optical upper limits
  15. EP250711a: Global MASTER-Net observations report
  16. GRB 250711A: DDOTI Optical Upper Limit
  17. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  18. Fermi GRB 250711A: Global MASTER-Net observations report
  19. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  20. GRB 250704A: GRANDMA observations
  21. GRB 250704A: SVOM/ECLAIRs refined analysis
  22. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  23. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  24. GRB 250702B,D,E / EP250702a: ALMA detection
  25. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  26. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  27. IceCube-250708A: No Candidates from WINTER
  28. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  29. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  30. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  31. EP/WXT 01709181970: GOTO observations confirm stellar variability
  32. EP250704a/GRB 250704B: 10 GHz VLA detection
  33. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  34. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  35. IceCube-250706A: No Candidates from WINTER
  36. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  37. GRB 250704B / EP250704a: VLA radio detection
  38. Fermi GRB 250708A: Global MASTER-Net observations report
  39. IceCube-250708A: Global MASTER-Net observations report
  40. EP250704a/GRB250704B : HCT optical and NIR upper limits
  41. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  42. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  43. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  44. GRB 250702F: radio detection with the VLA
  45. IceCube-250706A: EP-FXT follow-up observations
  46. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  47. IceCube-250706A: Global MASTER-Net observations report
  48. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  50. GRB 250706B: Swift/UVOT Detection
  51. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  52. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  53. GRB 250702F: GRANDMA observations
  54. GRB 250706B: refined SVOM/MXT data analysis
  55. GRB 250706A: Swift/UVOT Upper Limits
  56. GRB 250706B: REM optical observations
  57. GRB 250706A: REM optical/NIR observations
  58. IceCube-250416A: DDOTI Optical Upper Limit
  59. IceCube-250706A: COLIBRÍ optical upper limits
  60. Swift GRB 250706A: Global MASTER-Net observations report
  61. GRB 250706A: JinShan optical upper limits
  62. GRB 250706A: SAO RAS optical observations
  63. EP250704A: NOWT Detection
  64. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  65. GRB250706B: Swift-XRT counterpart detection
  66. GRB 250706B: iTelescope optical observations
  67. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  68. GRB 250706B: TRT bright optical counterpart detection
  69. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  70. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  71. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  72. GRB 250704B: Swift/UVOT Upper Limits
  73. GRB 250704A: Swift/UVOT Detection
  74. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  75. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  76. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  77. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  78. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  79. GRB 250702F: Kilonova-Catcher optical afterglow detection
  80. GRB 250702F: Monte Agliale Observatory optical observations
  81. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  82. EP250704a / GRB 250704B: JinShan optical observations
  83. EP250704a / GRB 250704B: SAO RAS optical observations
  84. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  85. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  86. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  87. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  88. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  89. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  90. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  91. EP250704a / GRB250704B: Swift-XRT counterpart detection
  92. GRB 250702B / EP2050702a: FTW optical and NIR observations
  93. EP250704a / GRB 250704B - REM observations
  94. GRB 250702F: GROWTH-India Telescope optical observations
  95. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  96. EP250702a: WFST optical observations
  97. EP250704a: COLIBRÍ optical counterpart candidate
  98. GRB 250702F: optical photometry from Konkoly
  99. GRB 250704A: REM detection of the optical afterglow
  100. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations

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