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"

32770 results found.

  1. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  2. GRB 250916A: Mondy R-band optical observations
  3. GRB 250919A: Glowbug gamma-ray detection
  4. GRB 250919A: Fermi GBM Observation
  5. Fermi GRB 250918A: Global MASTER-Net observations report
  6. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  7. GRB 250918A: SVOM/GRM observation
  8. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  9. GRB 250919A: Swift-XRT afterglow detection
  10. GRB 250919A: Fermi-LAT detection
  11. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  12. GRB 250919A: SVOM/GRM observation of a very bright GRB
  13. EP250919a: Global MASTER-Net observations report
  14. EP250919a: Einstein Probe detection of an X-ray transient
  15. Correction for GCN 41877: EP-WXT ID is 01709243841
  16. GRB 250916A: Fermi GBM Observation
  17. Fermi GRB 250919A: Global MASTER-Net observations report
  18. GRB 250916A: KAIT optical observations
  19. GRB 250917B: VLT/HAWK-I near-infrared observations
  20. GRB 250916A: NuSTAR detection of the prompt emission
  21. GRB 250916A: further SAO RAS optical observations
  22. GRB 250912A: SVOM/ECLAIRs refined analysis
  23. GRB 250917B: Swift-BAT refined analysis
  24. GRB 250917B: Swift/UVOT Upper Limits
  25. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  26. GRB 250916A: Swift-XRT observations
  27. EP250916a: EP-FXT follow-up observation
  28. GRB 250916A: MAO/AZT-22 optical observations
  29. GRB 250916A: SAO RAS optical observations
  30. GRB 250916A : GIT optical observations
  31. LIGO/Virgo/KAGRA S250917aq: Updated Sky localization
  32. GRB 250916A: Glowbug gamma-ray detection
  33. GRB250917B: WFST optical observations
  34. GRB 250916A: Swift ToO observations
  35. GRB 250917B: Fermi GBM Observation
  36. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  37. Fermi GRB 250917B: Global MASTER-Net observations report
  38. GRB 250916A: GOTO optical counterpart candidate
  39. GRB 250916A: AstroSat CZTI detection of a bright long burst
  40. GRB 250910A: SVOM/ECLAIRs refined analysis
  41. Fermi GRB 250916A: Global MASTER-Net observations report
  42. EP250827b: VLA Observations
  43. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  44. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  45. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  46. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  47. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  48. GRB 250912A: Swift-XRT observations
  49. GRB250912A: VLT/HAWK-I follow-up observations
  50. GRB 250912A: VLT observations
  51. GRB 250912A: Fermi GBM Observation
  52. GRB 250911A: Insight-HXMT detection
  53. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  54. GRB 250912A:SVOM/VT optical upper limit
  55. GRB 250912A: LCO optical upper limit
  56. Fermi GRB 250912A: Global MASTER-Net observations report
  57. EP250911a: Global MASTER-Net observations report
  58. GRB 250912A: SVOM detection of a burst
  59. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  60. EP250911a: Upper limit from Fermi-GBM Observations
  61. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  62. GRB 250911A: GECAM-B detection
  63. GRB 250911A: Swift-BAT refined analysis
  64. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  65. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  66. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  67. GRB 250910B: SVOM/GRM observation
  68. EP250911a: SVOM/VT optical observation
  69. GRB 250911A: MASTER optical counterpart observations
  70. EP250911a: SAO RAS optical observations
  71. EP250911a: Swift-XRT observations
  72. EP250911a: Optical detection with Kinder observations
  73. GRB 250911A: Swift/UVOT Detection
  74. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  75. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  76. GRB 250909B: Insight-HXMT detection
  77. GRB 250909B: SVOM/GRM observation
  78. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  79. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  80. EP250911a: COLIBRÍ optical observations
  81. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  82. Fermi GRB 250910B: Global MASTER-Net observations report
  83. EP250911a: LCO optical counterpart discovery
  84. EP250910a: Global MASTER-Net observations report
  85. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  86. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  87. GRB 250903A: SVOM/ECLAIRs refined analysis
  88. GRB 250911A: COLIBRÍ optical counterpart candidate
  89. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  90. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  91. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  92. GRB 250910A: SVOM/VT optical upper limit
  93. EP250908C: GROND observation of the fading optical counterpart
  94. GRB 250910A: LCO optical upper limit
  95. GRB 250909A: AstroSat CZTI detection
  96. GRB 250910A: SVOM/MXT possible afterglow detection
  97. GRB 250702B: Late time Chandra observations
  98. EP250908b/EP#01709240653: Swift/UVOT Detection
  99. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  100. GRB 250907A: CALET Gamma-Ray Burst Monitor detection

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