Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

16100 results found.

  1. IceCube-250406A: No candidates from the Zwicky Transient Facility
  2. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  3. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  4. IceCube 250406.951: DDOTI Optical Observations
  5. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  6. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  7. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  8. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  9. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  10. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  11. GRB 250404A / EP250404a: Mondy optical observations
  12. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  13. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  14. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  15. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  16. EP250402a: Optical upper limit with PD 1.3m observations
  17. GRB 250404A / EP250404a: NOT optical observations
  18. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  19. EP250404a: REM optical/NIR observations
  20. EP250404a: Seimei/TriCCS optical counterpart detection
  21. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  22. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  23. EP250404a: LCO optical counterpart detection
  24. EP250404a: Xinglong decaying optical counterpart
  25. GRB 250403A: Montarrenti Observatory optical detection
  26. GRB 250403A: KAIT optical observations
  27. EP250404a: AKO Optical Afterglow Detection
  28. EP250404a: LAST detection of optical counterpart
  29. EP250404a: Xinglong-2.16m spectroscopic redshift
  30. GRB 250327B: VIRT Optical Upper Limit
  31. EP250404a: Mephisto multi-band optical detection
  32. EP250321A: J band upper limit by SYSU 80cm telescope
  33. EP250404a: BOOTES-4/JGT optical afterglow detection
  34. EP250404a: Nanshan/HMT optical counterpart detection
  35. GRB 250402A: Mondy optical observations
  36. GRB 250403A: Swift/UVOT Detection
  37. GRB 250402A: Swift/UVOT Upper Limits
  38. EP250402a: Optical upper limit with Kinder observations
  39. GRB 250403A: SVOM/VT optical observation
  40. GRB 250403A: REM NIR afterglow detection
  41. GRB 250403A: LCO optical counterpart detection
  42. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  43. GRB 250403A: JinShan optical observations
  44. GRB 250402A: EP-FXT afterglow detection
  45. GRB 250403A: Optical counterpart detection by LCO.
  46. GRB 250403A: Swift-XRT observations
  47. GRB 250403A: GOTO optical counterpart follow-up observations
  48. GRB 250402A: NUTTelA-TAO Early Optical Limits
  49. GRB 250403A: GMG Optical Observation
  50. GRB 250403A: 1.6m Mephisto multi-band optical detection
  51. GRB 250403A: SVOM/C-GFT optical observations
  52. GRB 250403A: GOTO detection of the optical afterglow
  53. GRB 250402A: Swift-XRT observations
  54. GRB 250225B: VLT host galaxy redshift z = 0.950
  55. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  56. GRB 250402A: REM optical/NIR upper limits
  57. GRB 250402A: LCO optical counterpart detection
  58. GRB 250402A: SVOM/VT optical counterpart
  59. GRB 250402A: SVOM detection of a burst
  60. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  61. GRB 250314A: ALMA detection
  62. GRB 250329A: Swift/UVOT Upper Limit
  63. GRB 250327B: Swift/UVOT Detection
  64. GRB 250327A: Swift/UVOT Upper Limits
  65. GRB 250331E: SVOM/GRM observation
  66. GRB 250327B: Kilonova-Catcher Observations
  67. GRB250331D: AbAO optical observations
  68. GRB 250331C: Swift/UVOT Upper Limits
  69. GRB 250331B: Swift/UVOT Upper Limits
  70. GRB 250328A: AbAO AS-32 Optical Observations
  71. GRB 250219A: NOT candidate host galaxy detection
  72. GRB 250330B: SVOM/GRM observation of a short burst
  73. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  74. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  75. GRB 250329B: CAHA 2.2m telescope optical limit
  76. GRB20250327B: 45th Parallel Observatory upper limit
  77. GRB 250328A: Swift-XRT refined Analysis
  78. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  79. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  80. GRB 250330A: SVOM/VT optical upper limit
  81. GRB 250314A: VLA detection
  82. GRB 250330A: BOOTES-7 early optical upper limit
  83. GRB 250330A: Swift/UVOT Upper Limits
  84. GRB 250328A: 1.6m Mephisto optical observations
  85. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  86. GRB 250330A: VLT/FORS2 Optical Observations
  87. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  88. GRB 250329B: SVOM/C-GFT optical upper limit
  89. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  90. GRB 250327B: ALMA detection
  91. GRB 250327B: VLA detection
  92. GRB 250329B: SVOM/VT optical upper limit
  93. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  94. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  95. GRB250329A: REM optical afterglow detection
  96. GRB 250329B: GWAC-F50A optical upper limit
  97. GRB 250329A: Swift-XRT afterglow detection
  98. GRB 250328A: SVOM/VT optical observation
  99. GRB 250329A: Fading optical counterpart detection by LCO.
  100. GRB 250328A: SVOM/C-GFT optical upper limit

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