Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32766 results found.

  1. GRB 250702F: optical photometry from Konkoly
  2. GRB 250704A: REM detection of the optical afterglow
  3. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  4. GRB 250702F: SVOM/VT optical observation
  5. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  6. GRB 250702F: Swift/UVOT Detection
  7. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  8. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  9. Fermi GRB 250703A: Global MASTER-Net observations report
  10. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  11. GRB 250702F: Fermi GBM Observation
  12. GRB 250702F: Leavitt Observatory optical observations
  13. GRB 250702F: AKO Optical Afterglow Detection
  14. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  15. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  16. GRB 250702A: GECAM-B detection
  17. GRB 250702F: Skynet Optical Observations
  18. GRB 250424A: VIRT Optical Upper Limit
  19. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  20. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  21. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  22. GRB 250702F: TRT Optical Observation
  23. GRB 250703A: DDOTI Optical Upper Limit
  24. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  25. GRB 250702F: REM optical afterglow detection
  26. EP250702a: Global MASTER-Net observations report
  27. GRB 250702F: DDOTI Optical Observation
  28. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  29. GRB 250702F: COLIBRÍ Observations of the Afterglow
  30. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  31. Fermi GRB 250702E: Global MASTER-Net observations report
  32. Fermi GRB 250702B: Global MASTER-Net observations report
  33. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  34. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  35. GRB 250702F: NOT observations of the optical afterglow
  36. GRB 250702F: MASTER optical afterglow observation
  37. Fermi GRB 250702F: Global MASTER-Net observations report
  38. Fermi GRB 250702C: Global MASTER-Net observations report
  39. GRB 250702F: GOTO optical counterpart detection
  40. GRB 250702F: Swift detection of a burst with an optical counterpart
  41. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  42. Konus-Wind detection of GRB 250627A
  43. IPN triangulation of GRB 250627A (short)
  44. GRB 250702A: Fermi GBM Detection
  45. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  47. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  48. GRB 250628B: Swift-XRT observations
  49. GRB 250628B: SVOM/VT optical upper limit
  50. GRB 250628B: EP-FXT counterpart detection
  51. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  52. GRB 250627A: Insight-HXMT detection
  53. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  54. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  56. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  58. GRB 250628A: REM optical/NIR upper limits
  59. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  60. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  61. GRB 250628A: VLT/X-shooter upper limits
  62. GRB 250628A: Swift/UVOT Upper Limits
  63. Fermi GRB 250626A: Global MASTER-Net observations report
  64. Swift GRB 250628A: Global MASTER-Net observations report
  65. GRB 250625A: Swift-BAT refined analysis
  66. GRB 250625A: Leavitt Observatory afterglow detection
  67. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  68. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  69. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  70. GRB 250625A: SVOM/C-GFT upper limit in early phase
  71. GRB 250625A: GECAM-B detection
  72. GRB 250625A: Swift/UVOT Upper Limits
  73. GRB 250625A: ABObservatory afterglow detection
  74. GRB 250625A: OHP/T193 optical detection
  75. GRB 250625A: COLIBRÍ optical observations
  76. GRB 250625A: Fermi-LAT detection
  77. GRB 250625A: JinShan optical observations
  78. GRB250625A: Fermi GBM Observation
  79. Swift GRB 250625A: Global MASTER-Net observations report
  80. GRB 250625A: NOT z-band upper limit
  81. GRB 250625A: SVOM/VT optical confirmation
  82. GRB 250620B: Fermi GBM Observation
  83. GRB 250625A: SAO RAS possible optical afterglow
  84. Fermi GRB 250625A: Global MASTER-Net observations report
  85. GRB 250625A: Swift detection of a burst
  86. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  87. GRB 250620A: AstroSat CZTI detection
  88. GRB 241018A: Maidanak optical observations
  89. GRB 250620C: AstroSat CZTI detection
  90. Fermi GRB 250624A: Global MASTER-Net observations report
  91. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  92. Fermi GRB 250623A: Global MASTER-Net observations report
  93. GRB 250521A: VZLUSAT-2 detection
  94. GRB 250617B: Swift-BAT refined analysis
  95. Konus-Wind detection of GRB 250620C
  96. IPN triangulation of GRB 250620C (long/bright)
  97. GRB 250620C: SVOM/GRM observation
  98. GRB 250620A: SVOM/GRM observation of a short burst
  99. GRB250620A: Fermi GBM Observation
  100. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.

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