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"

32762 results found.

  1. GRB 251222A / EP251222b: GECAM-B observation
  2. EP251221a: Liverpool Telescope upper limits
  3. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  4. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  5. Konus-Wind detection of GRB 251222A / EP251222b
  6. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  7. EP251222a: NTT/ULTRACAM optical observations
  8. EP251222a: GOTO optical upper limit
  9. GRB 251222A / EP251222b: GOTO optical counterpart detection
  10. GRB 251222A / EP251222b: LCO optical observations
  11. GRB 251222A: 1.3m DFOT optical detection
  12. GRB251221A: 7DT optical upper limits
  13. EP251222a: GSP Optical Counterpart Detection
  14. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  15. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  16. EP251222b/GRB 251222A: SVOM/GRM observation
  17. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  18. EP251221a: Global MASTER-Net observations report
  19. GRB 251222A: PRIME near-infrared detection
  20. EP251221a: NOT optical upper limit
  21. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  22. GRB 251222A: NOT optical observations
  23. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  24. IPN triangulation of GRB 251220B (short)
  25. GRB 251222A: Swift ToO observations
  26. GRB 251222A: SVOM/VT optical candidate
  27. GRB 251222A: SVOM detection of a long burst
  28. EP251220a: PRIME upper limit
  29. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  30. GRB 251221A: PRIME near-infrared observation
  31. EP251220a: NOT optical observations
  32. EP251220a: FTW optical and NIR observations
  33. GRB 251221A: UAFO and Mondy optical upper limit
  34. GRB 251221A: Swift/UVOT Upper Limits
  35. GRB 251221A: Fermi GBM Observation
  36. EP251220a: EP-FXT follow-up observation
  37. GRB 251220B: SVOM/GRM observation of a short burst
  38. EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
  39. EP 251220a: GOTO optical counterpart detection
  40. GRB 251221A: COLIBRÍ detection of the optical counterpart
  41. EP 251220a: COLIBRÍ detection of the optical counterpart
  42. EP251220a: Global MASTER-Net observations report
  43. GRB 251219A: SVOM/GRM observation of a short burst
  44. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  45. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  46. IceCube-251218A: COLIBRÍ optical upper limits
  47. GRB 251214B: VIRT Optical Upper Limit
  48. Fermi GRB 251217A: Global MASTER-Net observations report
  49. GRB 251215A: Swift/UVOT Upper LImits
  50. GRB 251215A: Fermi GBM Observation
  51. Fermi GRB 251216A: Global MASTER-Net observations report
  52. GRB 251202A/EP251202a: Koshka optical upper limit
  53. GRB 251214B: Mondy optical upper limit
  54. GRB 251215A: COLIBRÍ optical upper limit
  55. EP251214b: KAIT optical upper limit
  56. Fermi GRB 251215A: Global MASTER-Net observations report
  57. EP251214a: Optical upper limit with Kinder observations
  58. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  59. GRB 251215A: Glowbug gamma-ray detection
  60. GRB 251214B: UAFO optical upper limit
  61. GRB 251214B: VLT/X-shooter observations
  62. GRB 251213A: GRID-10B observation
  63. GRB 251214B: Swift-BAT refined analysis
  64. GRB 251202A: radio detection with the VLA
  65. EP251214b: Global MASTER-Net observations report
  66. EP251214b : Einstein Probe detection of a fast X-ray transient
  67. EP251214b : Einstein Probe detection of a fast X-ray transient
  68. GRB 251214B: AbAO optical observations
  69. GRB 251214B: LCO detection of the optical counterpart
  70. GRB 251209A: GECAM-B observation of a long burst
  71. GRB 251214D: GECAM-B observation of a long burst
  72. GRB 251214B: Fermi GBM Observation
  73. GRB 251209A: Insight-HXMT/HE detection
  74. GRB 251215A: Swift ToO observations
  75. EP251214b (EP trigger 01709250023): LCO optical limits
  76. GRID detection of GRB 251213A
  77. GRB 251203B: AbAO optical observations
  78. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  79. GRB 251214B: GECAM-B observation of a long burst
  80. GRB 251213A: SVOM/GRM observation
  81. EP251214a: KAIT optical upper limit
  82. GRB 251213A: AstroSat CZTI detection
  83. GRB 251214A: AstroSat CZTI detection
  84. GRB 251214B: Swift/UVOT Detection
  85. GRB 251214B: COLIBRÍ observations of the afterglow
  86. EP251214a: EP-FXT non-detection and upper limit
  87. GRB 251214A: GECAM-B observation of a likely long burst
  88. GRB 251214B: 1.3m DFOT optical detection
  89. EP251214a: Global MASTER-Net observations report
  90. GRB 251214B: Xinglong-2.16m optical observation
  91. GRB 251214B : MASTER optical afterglow detection
  92. GRB 251214B: SVOM/C-GFT optical observations
  93. EP251214a: COLIBRÍ optical upper limit
  94. Swift GRB 251214B: Global MASTER-Net observations report
  95. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  96. Fermi GRB 251214A: Global MASTER-Net observations report
  97. EP251212a: Global MASTER-Net observations report
  98. EP251212a: KAIT optical upper limit
  99. EP251212a / GRB 251212A: AstroSat CZTI detection
  100. EP251212a: EP-FXT follow-up 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