Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

45423 results found.

  1. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  2. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  3. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  4. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  5. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  6. EP 250704a: BOOTES-5 optical detection
  7. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  8. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  9. GRB 250702A: Insight-HXMT detection
  10. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  11. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  12. EP250704a / GRB250704B: Swift-XRT counterpart detection
  13. GRB 250704A: Swift-XRT afterglow detection
  14. GRB 250702B / EP2050702a: FTW optical and NIR observations
  15. Konus-Wind detection of GRB 250702F
  16. EP250704a / GRB 250704B - REM observations
  17. GRB 250702F: GROWTH-India Telescope optical observations
  18. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  19. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  20. EP250702a: WFST optical observations
  21. EP250704a: COLIBRÍ optical counterpart candidate
  22. EP250704a: Einstein Probe detection of an X-ray transient
  23. GRB 250704B: SVOM/GRM observation of a short burst
  24. GRB 250702F: optical photometry from Konkoly
  25. GRB 250704A: REM detection of the optical afterglow
  26. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  27. GRB 250702F: SVOM/VT optical observation
  28. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  29. GRB 250704A: SVOM detection of a burst
  30. GRB 250702F: Swift/UVOT Detection
  31. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  32. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  33. Fermi GRB 250703A: Global MASTER-Net observations report
  34. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  35. GRB 250702F: Swift-XRT refined Analysis
  36. GRB 250702F: Fermi GBM Observation
  37. GRB 250702F: Leavitt Observatory optical observations
  38. GRB 250702F: AKO Optical Afterglow Detection
  39. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  40. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  41. GRB 250702A: GECAM-B detection
  42. GRB 250702F: Skynet Optical Observations
  43. GRB 250424A: VIRT Optical Upper Limit
  44. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  45. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  46. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  47. GRB 250702F: TRT Optical Observation
  48. GRB 250703A: DDOTI Optical Upper Limit
  49. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  50. GRB 250702F: REM optical afterglow detection
  51. EP250702a: Global MASTER-Net observations report
  52. GRB 250702F: DDOTI Optical Observation
  53. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  54. GRB 250703A: Fermi GBM Final Real-time Localization
  55. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  56. GRB 250702F: COLIBRÍ Observations of the Afterglow
  57. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  58. Fermi GRB 250702E: Global MASTER-Net observations report
  59. Fermi GRB 250702B: Global MASTER-Net observations report
  60. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  61. GRB 250702F: Enhanced Swift-XRT position
  62. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  63. GRB 250702F: NOT observations of the optical afterglow
  64. GRB 250702F: MASTER optical afterglow observation
  65. Fermi GRB 250702F: Global MASTER-Net observations report
  66. Fermi GRB 250702C: Global MASTER-Net observations report
  67. GRB 250702F: GOTO optical counterpart detection
  68. GRB 250702F: Ondrejov D50 optical afterglow detection
  69. GRB 250702F: Swift detection of a burst with an optical counterpart
  70. Swift GRB 250702F: Global MASTER-Net observations report
  71. GRB 250702F: Fermi GBM Final Real-time Localization
  72. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  73. GRB 250702E: Fermi GBM Final Real-time Localization
  74. Konus-Wind detection of GRB 250627A
  75. IPN triangulation of GRB 250627A (short)
  76. GRB 250702A: Fermi GBM Detection
  77. GRB 250702D: Fermi GBM Final Localization Correction
  78. GRB 250702C: Fermi GBM Final Real-time Localization
  79. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  80. GRB 250702B: Fermi GBM Final Real-time Localization
  81. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  82. GRB 250702A: Fermi GBM Final Real-time Localization
  83. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  85. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  86. GRB 250628B: Swift-XRT observations
  87. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  88. GRB 250628B: SVOM/VT optical upper limit
  89. GRB 250628B: EP-FXT counterpart detection
  90. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  91. GRB 250627A: Insight-HXMT detection
  92. GRB 250627A: SVOM/GRM detection of a short burst
  93. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  94. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  96. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  98. GRB 250628A: REM optical/NIR upper limits
  99. GRB 250628C: Fermi GBM Final Real-time Localization
  100. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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