Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"
  1. GRB 251116C: SVOM/VT optical upper limit
  2. GRB 251025B: further Mondy optical observations
  3. GRB 251111A: Mondy optical upper limit
  4. GRB 251116B: EP-FXT follow-up observation
  5. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  7. GRB 251116B: LCO optical upper limits
  8. GRB 251116C: LCO optical upper limits
  9. SVOM GRB251116C: Global MASTER-Net observations report
  10. GRB 251116C: SVOM detection of a burst
  11. GRB 251116B: SVOM detection of a burst
  12. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 251116A: Fermi GBM Final Real-time Localization
  14. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  15. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  16. GRB 251115A: Tiled Swift observations
  17. GRB 251115A: Fermi-LAT detection
  18. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  19. Fermi GRB 251115A: Global MASTER-Net observations report
  20. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  21. GRB 251115A: Fermi GBM Final Real-time Localization
  22. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  23. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  24. GRB 251113A: Glowbug gamma-ray detection
  25. GRB 251113A: AstroSat CZTI detection
  26. GRB 251114B: Fermi GBM Final Real-time Localization
  27. GRB 251112A: Swift-BAT refined analysis
  28. Konus-Wind detection of GRB 251108C
  29. Fermi trigger No 784717756: Global MASTER-Net observations report
  30. Konus-Wind detection of GRB 251103A
  31. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  32. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  33. IPN triangulation of GRB 251108C
  34. The EP-WXT trigger 01709248221 is likely a flaring star
  35. Fermi GRB 251114A: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  37. GRB 251114A: Fermi GBM Final Real-time Localization
  38. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  39. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  40. Fermi GRB 251113A: Global MASTER-Net observations report
  41. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  42. GRB 251113A: Fermi GBM Final Real-time Localization
  43. GRB 251111A: SVOM/ECLAIRs refined analysis
  44. GRB 251025B: SVOM/ECLAIRs refined analysis
  45. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  46. GRB 251112A: Swift/UVOT Upper Limits
  47. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  48. GRB 251112A: Swift-XRT refined Analysis
  49. GRB 251108C: AstroSat CZTI detection
  50. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  51. GRB 251112B: MAXI/GSC detection
  52. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  53. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  54. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  55. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  56. GRB 251108B: Glowbug gamma-ray detection
  57. Swift Trigger 1413695: a possible GRB 251112A
  58. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  59. Fermi trigger No 784621743: Global MASTER-Net observations report
  60. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  61. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  62. GRB251111A: 1.3m DFOT optical upper limit
  63. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  64. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  65. GRB 251111A: Swift-XRT afterglow detection
  66. GRB 251111A: SVOM/VT optical observations with X-band data
  67. SVOM GRB251111.42: Global MASTER-Net observations report
  68. GRB 251111A: Swift-XRT observations
  69. SVOM GRB251111.22: Global MASTER-Net observations report
  70. GRB 251111A: EP-FXT counterpart detection
  71. GRB 251013C: Chandra X-ray observations and jet break detection
  72. GRB 251111A: SVOM/VT optical observations with VHF data
  73. GRB 251111A: KAIT optical upper limit
  74. GRB 251111A: LCO optical observation
  75. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  76. GRB 251111A: SVOM detection of a soft burst
  77. GRB 251103B: Swift-BAT refined analysis
  78. GRB 251106A: Swift/UVOT Upper Limits
  79. GRB 251105B: Insight-HXMT/HE detection
  80. GRB 251106B: Insight-HXMT detection
  81. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  82. GRB 251105A: AstroSat CZTI detection
  83. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  84. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  85. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  86. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  87. GRB 251108A: Fermi GBM Final Localization Correction
  88. Fermi trigger No 784329591: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  90. Fermi trigger No 784279167: Global MASTER-Net observations report
  91. SVOM GRB251108.54: Global MASTER-Net observations report
  92. GRB 251102B: SVOM/GRM observation
  93. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  94. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  95. The EP-WXT trigger 01709248051 is likely a flaring star
  96. SVOM GRB251106.83: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  98. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  99. IPN triangulation of GRB 251105B (possible sGRB with EE)
  100. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart

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