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"

16203 results found.

  1. GRB 250330B: SVOM/GRM observation of a short burst
  2. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  3. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  4. GRB 250329B: CAHA 2.2m telescope optical limit
  5. GRB20250327B: 45th Parallel Observatory upper limit
  6. GRB 250328A: Swift-XRT refined Analysis
  7. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  8. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  9. GRB 250330A: SVOM/VT optical upper limit
  10. GRB 250314A: VLA detection
  11. GRB 250330A: BOOTES-7 early optical upper limit
  12. GRB 250330A: Swift/UVOT Upper Limits
  13. GRB 250328A: 1.6m Mephisto optical observations
  14. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  15. GRB 250330A: VLT/FORS2 Optical Observations
  16. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  17. GRB 250329B: SVOM/C-GFT optical upper limit
  18. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  19. GRB 250327B: ALMA detection
  20. GRB 250327B: VLA detection
  21. GRB 250329B: SVOM/VT optical upper limit
  22. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  23. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  24. GRB250329A: REM optical afterglow detection
  25. GRB 250329B: GWAC-F50A optical upper limit
  26. GRB 250329A: Swift-XRT afterglow detection
  27. GRB 250328A: SVOM/VT optical observation
  28. GRB 250329A: Fading optical counterpart detection by LCO.
  29. GRB 250328A: SVOM/C-GFT optical upper limit
  30. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  31. GRB 250329A: VLT/X-shooter redshift z = 2.921
  32. GRB 250329A: SVOM/VT optical counterpart confirmation
  33. GRB 250329A: SVOM detection of a burst
  34. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  35. GRB 250327B: J-band observations with WINTER
  36. GRB 250327B: MASTER detection of OT rebrightening
  37. GRB 250327B: LCO optical counterpart detection
  38. GRB 250328A: GWAC-F50A optical upper limit
  39. FRB 20250316A: FTW optical observations
  40. GRB 250327B: CrAO and SAO RAS Optical Observations
  41. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  42. GRB 250327B: further optical observations by LCOGT
  43. EP250315a: Pan-STARRS r and i-band imaging and photometry
  44. GRB 250327b: Liverpool Telescope optical observations
  45. GRB 250322A: GRANDMA/TNOT optical upper limits
  46. GRB 250327B: Las Cumbres optical counterpart detection
  47. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  48. GRB 250327B: 1.6m Mephisto optical observations
  49. GRB 250327B: NOT spectroscopic redshift z = 3.035
  50. GRB 250327B: GOTO optical counterpart detection
  51. GRB 250327B: SVOM/VT optically bright counterpart
  52. GRB 250327B: SAO RAS optical candidate
  53. GRB 250327B: SVOM detection of a burst
  54. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  55. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  56. GRB 250327A: SVOM/VT optical candidate
  57. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  58. GRB 250327A: DDOTI Optical Observations
  59. GRB 250327A: COLIBRÍ optical upper limit
  60. EP250321a: Mondy AZT-33IK Continued Optical Observations
  61. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  62. GRB 250322A: third epoch of NOT optical observations
  63. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  64. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  65. GRB 250322A: further NOT optical observations
  66. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  67. GRB 250322A: Swift/UVOT Upper Limits
  68. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  69. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  70. EP250321a: TNOT Observation of Optical Counterpart
  71. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  72. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  73. GRB250322A: STEP/T80S optical limits
  74. GRB 250322A: Gemini-South optical observations
  75. GRB 250322A: VLT optical observations
  76. FRB 250316A: DDOTI Continued Optical Observations
  77. GRB 250322A: NOT optical upper limits
  78. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  79. GRB 250322A: MASTER optical observation
  80. EP250321a: Liverpool Telescope optical follow-up
  81. EP250321a: Mondy AZT-33IK Optical Observations
  82. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  83. EP250321a: KAIT optical observations
  84. EP250321A: COLIBRÍ Continuing Optical Observations
  85. EP250321a: WFST optical observations
  86. EP250321a: Xinglong 216 decaying optical observations
  87. EP250321a: SVOM/VT optical observation
  88. EP 250321A: Optical counterpart detection by LCO.
  89. EP250321a: Kinder optical follow-up observations
  90. GRB 250321A: Swift/UVOT Upper Limits
  91. GRB 250320B: SVOM/GRM observation of a long burst
  92. EP250321a: LCO optical counterpart detection
  93. EP250321a: Swift-XRT detection of an X-ray source
  94. EP250321A: COLIBRÍ Optical Observations
  95. EP250321a: VLT/X-shooter redshift z = 4.368
  96. EP250321a: REM optical/NIR afterglow detection
  97. EP250321a: BOOTES-5/JGT optical afterglow detection
  98. EP250321a: TRT optical counterpart detection
  99. GRB 250321A: GOTO optical upper limits
  100. EP250226a/GRB 250226A: KAIT optical 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