Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"

3548 results found.

  1. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  2. EP251222a: Global MASTER-Net observations report
  3. GRB 251222A: 1.3m DFOT optical detection
  4. GRB251221A: 7DT optical upper limits
  5. EP251222b/GRB 251222A: SVOM/GRM observation
  6. GRB 251221A: Fermi GBM Observation
  7. GRB 251221A: Fermi GBM Final Real-time Localization
  8. EP251220a: Global MASTER-Net observations report
  9. IceCube Alert 251218.85: Global MASTER-Net observations report
  10. Fermi GRB 251216A: Global MASTER-Net observations report
  11. GRB 251214B: Mondy optical upper limit
  12. Fermi GRB 251215A: Global MASTER-Net observations report
  13. EP251214b: Global MASTER-Net observations report
  14. GRB 251214B: COLIBRÍ observations of the afterglow
  15. Fermi trigger No 787396657: Global MASTER-Net observations report
  16. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  17. IPN triangulation of GRB 251129B (short/hard)
  18. GRB 251130B: AstroSat CZTI detection
  19. GRB 251201B: Swift detection of a burst with an optical counterpart
  20. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  21. Fermi GRB 251130B: Global MASTER-Net observations report
  22. EP251130a: COLIBRÍ optical counterpart candidate
  23. GRB 251128A: AstroSat CZTI detection
  24. GRB 251126A: SAO RAS optical observations
  25. GRB 251128A: Fermi GBM Observation
  26. Fermi GRB 251128A: Global MASTER-Net observations report
  27. GRB 251126A: further SAO RAS optical observations
  28. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  29. GRB 251128A: Fermi GBM Final Real-time Localization
  30. Fermi GRB 251125A: Global MASTER-Net observations report
  31. EP251118a: Xinglong-2.16m optical observation
  32. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  33. GRB 251018A: FRAM-Auger optical detection
  34. LAT GRB251118.86: Global MASTER-Net observations report
  35. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  36. GRB 251115A: Swift-XRT observations
  37. GRB 251116C: Swift-XRT observations
  38. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  39. GRB 251116C: SVOM/VT optical upper limit
  40. GRB 251025B: further Mondy optical observations
  41. Fermi GRB 251115A: Global MASTER-Net observations report
  42. GRB 251112A: Swift-BAT refined analysis
  43. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  44. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  45. Fermi GRB 251114A: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  47. Swift Trigger 1413695: a possible GRB 251112A
  48. GRB 251111A: SVOM/VT optical observations with X-band data
  49. GRB 251105A: AstroSat CZTI detection
  50. SVOM GRB251108.54: Global MASTER-Net observations report
  51. SVOM GRB251106.83: Global MASTER-Net observations report
  52. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  53. GRB 251104A: SVOM detection of a burst
  54. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  55. Fermi GRB 251103A: Global MASTER-Net observations report
  56. Fermi GRB 251102A: Global MASTER-Net observations report
  57. GRB 251028A: Fermi GBM Observation
  58. GRB 251026B: LBT near-infrared observations
  59. GRB 251028B: Fermi/GBM observation
  60. GRB 251028B: Glowbug gamma-ray detection
  61. GRB 251028A: Glowbug gamma-ray detection
  62. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  63. Fermi GRB 251028B: Global MASTER-Net observations report
  64. GRB 251028B: Fermi GBM Final Localization Correction
  65. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  66. GRB 251028A: MAXI/GSC detection
  67. GRB 251028A: Fermi GBM Final Real-time Localization
  68. The EP-WXT trigger 01709247525 is not a real source
  69. EP251023b: Global MASTER-Net observations report
  70. Fermi GRB 251023A: Global MASTER-Net observations report
  71. EP/WXT 01709247295: GOTO optical afterglow candidate.
  72. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  73. EP251021b: Einstein Probe detection of a fast X-ray transient
  74. IceCube-251018A: Global MASTER-Net observations report
  75. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  76. Fermi GRB 251016B: Global MASTER-Net observations report
  77. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  78. sb25101602: Swift-XRT counterpart detection
  79. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  80. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  81. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  82. GRB 251014A: Fermi GBM Observation
  83. GRB 251014A: Swift detection of a possibly-short burst
  84. GRB 251014A: Fermi GBM Final Real-time Localization
  85. Fermi GRB 251013C: Global MASTER-Net observations report
  86. Fermi GRB 251013B: Global MASTER-Net observations report
  87. Fermi GRB 251011A: Global MASTER-Net observations report
  88. GRB 250919A: TERI gamma-ray detection
  89. Fermi GRB 251006B: Global MASTER-Net observations report
  90. GRB 251005C: AstroSat CZTI detection
  91. GRB 251003A: Swift-BAT refined analysis
  92. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  93. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  94. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  95. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  97. GRB 250924A: J-band detection with WINTER
  98. GRB 250920B: CrAO ZTSH optical observations
  99. Fermi trigger No 780156732: Global MASTER-Net observations report
  100. IPN triangulation of GRB 250920A (long/bright)

Advanced

Download all Circulars as a .tar.gz archive:
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