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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"

3137 results found.

  1. Swift Trigger 1513439 is probably not a GRB
  2. GRB 260924A: Optical follow-up observations with Kinder
  3. GRB 260924A: AstroSat CZTI detection
  4. Fermi GRB 260923A: Global MASTER-Net observations report
  5. GRB 260917C: AstroSat CZTI detection
  6. GRB 260921A: AstroSat CZTI detection
  7. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  8. GRB 260920A: AstroSat CZTI detection
  9. EP260920b: LCO optical counterpart detection
  10. EP Alert 260921.01: Global MASTER-Net observations report
  11. EP260917a: Global MASTER-Net observations report
  12. EP Alert 260918.24: Global MASTER-Net observations report
  13. SVOM GRB260918.16: Global MASTER-Net observations report
  14. Konus-Wind detection of GRB 260916B (short/hard)
  15. IPN triangulation of GRB 260916B (short)
  16. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 260915A: SVOM/ECLAIRs refined analysis
  18. MAXI GRB260916.37: Global MASTER-Net observations report
  19. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. GRB 260915A: LCO optical upper limits
  21. EP Alert 260914.53: Global MASTER-Net observations report
  22. GRB 260915A: SVOM detection of a burst
  23. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  24. SVOM GRB260914.47: Global MASTER-Net observations report
  25. GRB 260910B: GOTO tentative optical counterpart candidates
  26. GRB 260910B: Fermi GBM Final Real-time Localization
  27. EP Alert 260909.53: Global MASTER-Net observations report
  28. Fermi GRB 260907A: Global MASTER-Net observations report
  29. GRB260903A: Liverpool Telescope optical observations
  30. GRB 260903A: SVOM/VT optical candidate
  31. EP260901a: Global MASTER-Net observations report
  32. GRB 260829A: AstroSat CZTI detection
  33. GRB 260827A: Glowbug gamma-ray detection
  34. GRB 260825A: AstroSat CZTI detection
  35. GRB 260827A: Fermi GBM Final Real-time Localization
  36. IceCube Alert 260825A: Global MASTER-Net observations report
  37. The EP-WXT trigger 01709287395 is likely a flaring star
  38. EP260806a: SVOM/ECLAIRs detection through targeted search
  39. EP260806a: NUTTELA-TAO optical observations
  40. GRB 260810A: AstroSat CZTI detection of a long burst
  41. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  42. GRB 260808A: Fermi GBM Final Real-time Localization
  43. SN 2026stf / GRB 260708A: ATLAS forced photometry
  44. GRB 260803A: Fermi GBM Final Real-time Localization
  45. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  46. GRB 260731A: AstroSat CZTI detection of a long burst
  47. GRB 260730B: AstroSat CZTI detection
  48. GRB 260727A: AstroSat CZTI detection
  49. Fermi GRB 260726A: Global MASTER-Net observations report
  50. GRB 260723A: Fermi GBM Final Localization
  51. GRB 260718A: SVOM/VT optical upper limits
  52. SVOM sb26071506: Global MASTER-Net observations report
  53. GRB 260710A: AstroSat CZTI detection
  54. GRB 260709A: AstroSat CZTI detection
  55. GRB 260714B: AstroSat CZTI detection
  56. GRB 260714B: Fermi GBM Final Real-time Localization
  57. GRB 260708A: GRANDMA Optical Observations
  58. GRB 260705C: AstroSat CZTI detection
  59. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  60. LAT GRB260708.42: Global MASTER-Net observations report
  61. GRB 260706A: SVOM/VT optical upper limits
  62. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  63. GRB 260707A: Fermi GBM Final Real-time Localization
  64. IPN triangulation of GRB 260627A
  65. GRB 260629A: AstroSat CZTI detection
  66. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  67. Fermi trigger No 804552016: Global MASTER-Net observations report
  68. GRB 260616B: AstroSat CZTI detection
  69. GRB 260616A: AstroSat CZTI detection
  70. GRB 260506B: cubesat Avion detection
  71. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  72. GRB260616C: MAXI/GSC detection
  73. GRB 260614A: AstroSat CZTI detection
  74. GRB 260603C: AstroSat CZTI detection
  75. EP260605a: COLIBRÍ optical upper limits
  76. GRB 260604C: AstroSat CZTI detection
  77. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  78. GRB 260607B: AstroSat CZTI detection
  79. The EP-WXT trigger 01709267001 is likely a flaring star
  80. GRB 260601B / EP260601a: AstroSat CZTI detection
  81. EP260603a: Global MASTER-Net observations report
  82. Fermi GRB 260602B: Global MASTER-Net observations report
  83. Fermi GRB 260602B: Global MASTER-Net observations report
  84. GRB 260602A: Fermi GBM Final Real-time Localization
  85. Fermi trigger No 801900520: Global MASTER-Net observations report
  86. GRB 260531A: MAXI/GSC detection
  87. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  88. GRB 260526A: GECAM-B observation
  89. GRB 260525A: AstroSat CZTI detection
  90. Fermi GRB 260526A: Global MASTER-Net observations report
  91. GRB 260525A: Fermi GBM Final Real-time Localization
  92. GRB 260523B: AstroSat CZTI detection
  93. GRB 260511A: iTelescope T-75 optical detection
  94. GRB 260518A: AstroSat CZTI detection of a long burst
  95. GRB 260515A: further Liverpool Telescope observations
  96. Fermi GRB 260516C: Global MASTER-Net observations report
  97. GRB 260515A: Liverpool Telescope optical detection
  98. GRB 260515A: LCO optical observations
  99. SVOM GRB 260515A: Global MASTER-Net observations report
  100. EP260514a: Global MASTER-Net observations report

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