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"

20388 results found.

  1. GRB 250322A: 10 GHz VLA radio upper limits
  2. GRB 250402A: NUTTelA-TAO Early Optical Limits
  3. GRB 250403A: GMG Optical Observation
  4. GRB 250403A: 1.6m Mephisto multi-band optical detection
  5. GRB 250403A: SVOM/C-GFT optical observations
  6. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  7. GRB 250402A: REM optical/NIR upper limits
  8. GRB 250402A: LCO optical counterpart detection
  9. EP250402a: Einstein Probe detection of a fast X-ray transient
  10. GRB 250402A: SVOM/VT optical counterpart
  11. GRB 250402A: SVOM detection of a burst
  12. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  13. GRB 250329B: Swift/UVOT Upper Limit
  14. GRB 250329A: Swift/UVOT Upper Limit
  15. GRB 250327B: Swift/UVOT Detection
  16. GRB 250327A: Swift/UVOT Upper Limits
  17. GRB 250331E: SVOM/GRM observation
  18. GRB 250327B: Kilonova-Catcher Observations
  19. GRB250331D: AbAO optical observations
  20. GRB 250331C: Swift/UVOT Upper Limits
  21. GRB 250331B: Swift/UVOT Upper Limits
  22. GRB 250328A: AbAO AS-32 Optical Observations
  23. GRB 250219A: NOT candidate host galaxy detection
  24. GRB 250331D: Swift-XRT observations
  25. GRB 250331B: Swift-XRT refined Analysis
  26. GRB 250331B: Swift-XRT refined Analysis
  27. GRB 250330B: SVOM/GRM observation of a short burst
  28. Fermi GRB 250331E: Global MASTER-Net observations report
  29. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  30. GRB 250331C: Enhanced Swift-XRT position
  31. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 250331B: Enhanced Swift-XRT position
  33. GRB 250320C : SVOM detection of a burst through offline search
  34. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  35. GRB 250330A: VLT/FORS2 Afterglow Detection
  36. GRB20250327B: 45th Parallel Observatory upper limit
  37. GRB 250328A: Swift/UVOT Detection
  38. GRB 250328A: Swift-XRT refined Analysis
  39. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  40. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  41. GRB 250331C: Swift detection of a burst
  42. GRB 250331B: Swift detection of a burst
  43. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  44. GRB 250330A: Swift/UVOT Upper Limits
  45. GRB 250330A: Swift-XRT afterglow detection
  46. GRB 250328A: 1.6m Mephisto optical observations
  47. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  48. GRB 250330A: VLT/FORS2 Optical Observations
  49. GRB 250330A: Prompt Swift-XRT position
  50. GRB 250329B: Swift-XRT afterglow detection
  51. GRB 250330A: Swift detection of a burst
  52. GRB 250329B: SVOM/C-GFT optical upper limit
  53. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  54. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  55. GRB250329A: REM optical afterglow detection
  56. GRB 250329B: GWAC-F50A optical upper limit
  57. GRB 250329A: Swift-XRT afterglow detection
  58. GRB 250328A: SVOM/VT optical observation
  59. GRB 250329A: Fading optical counterpart detection by LCO.
  60. GRB 250328A: SVOM/C-GFT optical upper limit
  61. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  62. GRB 250329A: VLT/X-shooter redshift z = 2.921
  63. GRB 250329A: SVOM/VT optical counterpart confirmation
  64. GRB 250329A: SVOM detection of a burst
  65. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  66. GRB 250327B: J-band observations with WINTER
  67. GRB 250327B: LCO optical counterpart detection
  68. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  69. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  70. GRB 250327B: CrAO and SAO RAS Optical Observations
  71. EP250315a: Pan-STARRS r and i-band imaging and photometry
  72. GRB 250327b: Liverpool Telescope optical observations
  73. GRB 250322A: GRANDMA/TNOT optical upper limits
  74. GRB 250327A: SVOM/VT upper limits on the XRT position
  75. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  76. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  77. GRB 250327B: Las Cumbres optical counterpart detection
  78. GRB 250327B: 1.6m Mephisto optical observations
  79. GRB 250327B: NOT spectroscopic redshift z = 3.035
  80. GRB 250327B: SVOM/VT optically bright counterpart
  81. GRB 250327B: SAO RAS optical candidate
  82. GRB 250327B: SVOM detection of a burst
  83. GRB 250327A: J-band observations with WINTER
  84. GRB 250327A: SVOM/VT optical candidate
  85. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  86. GRB 250327A: DDOTI Optical Observations
  87. GRB 250327A: COLIBRÍ optical upper limit
  88. IPN triangulation of GRB 250322B
  89. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  90. EP250321a: Mondy AZT-33IK Continued Optical Observations
  91. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  92. GRB 250322A: third epoch of NOT optical observations
  93. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  94. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  95. GRB 250322A: further NOT optical observations
  96. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  97. GRB 250322A: Swift/UVOT Upper Limits
  98. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  99. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  100. GRB 250321B: Swift-XRT observations

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