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"

15360 results found.

  1. GRB 251128A: GECAM-B detection
  2. GRB 251128A: SVOM/GRM observation of a long burst
  3. GRB 251128A: Insight-HXMT/HE detection
  4. GRB 251129A: Swift ToO observations
  5. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  6. GRB 251129A: SVOM detection of a burst
  7. GRB 251129A: SVOM detection of a burst
  8. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  9. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  10. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  11. GRB 251126A NUTTelA-TAO Early Measurements
  12. EP251124a: Pan-STARRS ri-band imaging and photometry
  13. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  14. GRB 251126A: NOT optical observations
  15. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  16. GRB 251125B: GECAM-B detection
  17. GRB 251126A: Kilonova-Catcher optical afterglow detection
  18. GRB 251126A: Nanshan/HMT optical afterglow detection
  19. GRB 251126A: Swift detection of a burst
  20. EP251124a: NOT r- and z-band optical upper limits
  21. GRB 251124A: Fermi GBM Localization by automated pipeline
  22. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  23. EP251124a: Optical upper limit with Kinder observations
  24. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  25. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  26. EP251124a: Einstein Probe detection of an X-ray transient
  27. GRB 251116C: Swift-XRT confirmation of fading
  28. GRB 251122A / EP251122a: EP-FXT counterpart detection
  29. GRB 251122A / EP251122a: WFST optical observations
  30. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  31. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  32. GRB 251122A / EP251122a: LCO optical upper limits
  33. GRB 251122A / EP251122a: SVOM detection of a long burst
  34. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  35. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  36. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  37. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  38. GRB 251118A: GECAM-B detection
  39. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  40. EP251118a / GRB 251118C: SVOM/VT optical observation
  41. The EP-WXT trigger 01709248403 is likely a flaring star
  42. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  43. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  44. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  45. Konus-Wind detection of GRB 251118C (EP251118a)
  46. GRB 251117A: Insight-HXMT/HE detection
  47. GRB 251116D: SVOM/GRM observation of a long GRB
  48. GRB 251119A: SVOM detection of a possible burst
  49. EP251118a: preliminary result of EP-FXT follow-up observation
  50. GRB 251118A: Fermi-LAT detection
  51. GRB 251118A: Swift ToO observations
  52. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  53. GRB 251116C: SVOM/ECLAIRs refined analysis
  54. GRB 251116B: SVOM/ECLAIRs refined analysis
  55. GRB 251117A: AstroSat CZTI detection
  56. GRB 251114B: Insight-HXMT/HE detection
  57. GRB 251114B: GECAM-B detection of a short burst
  58. GRB 251117A: Fermi GBM observation
  59. GRB 251116D: Insight-HXMT/HE detection
  60. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  61. GRB 251117A: SVOM/GRM observation of a short burst
  62. GRB 251117A: Tiled Swift observations
  63. GRB 251117A: Fermi-LAT detection
  64. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  65. GRB 251116B: SVOM/VT optical upper limit
  66. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  67. GRB 251116D: AstroSat CZTI detection
  68. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  69. GRB 251116C: SVOM detection of a burst
  70. GRB 251116B: SVOM detection of a burst
  71. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  72. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  73. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  74. GRB 251115A: Tiled Swift observations
  75. GRB 251115A: Fermi-LAT detection
  76. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  77. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  78. GRB 251113A: AstroSat CZTI detection
  79. Konus-Wind detection of GRB 251108C
  80. Konus-Wind detection of GRB 251103A
  81. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  82. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  83. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  84. GRB 251111A: SVOM/ECLAIRs refined analysis
  85. GRB 251025B: SVOM/ECLAIRs refined analysis
  86. GRB 251108C: AstroSat CZTI detection
  87. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  88. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  89. GRB 251111A: Swift-XRT observations
  90. GRB 251111A: EP-FXT counterpart detection
  91. GRB 251013C: Chandra X-ray observations and jet break detection
  92. GRB 251111A: SVOM/VT optical observations with VHF data
  93. GRB 251111A: KAIT optical upper limit
  94. GRB 251111A: LCO optical observation
  95. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  96. GRB 251111A: SVOM detection of a soft burst
  97. GRB 251105B: Insight-HXMT/HE detection
  98. GRB 251106B: Insight-HXMT detection
  99. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  100. GRB 251105A: AstroSat CZTI detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov