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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"

25668 results found.

  1. GRB 251126A: GIT discovery of the likely optical afterglow
  2. GRB 251126A: Swift detection of a burst
  3. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  4. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  5. EP251124b: NOT r- and z-band optical upper limits
  6. Fermi GRB 251125B: Global MASTER-Net observations report
  7. GRB 251125B: Fermi GBM Final Real-time Localization
  8. EP251124b: Global MASTER-Net observations report
  9. EP251124a: Xinglong GWAC-F60A optical observation
  10. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  11. Fermi GRB 251125A: Global MASTER-Net observations report
  12. GRB 251125A: Fermi GBM Final Real-time Localization
  13. EP251124a: NOT r- and z-band optical upper limits
  14. EP251124a: Global MASTER-Net observations report
  15. EP251124a: Swift-XRT observations
  16. GRB 251124A: Fermi GBM Localization by automated pipeline
  17. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  18. EP251124a: Optical upper limit with Kinder observations
  19. GRB 251122B: Fermi GBM Final Localization
  20. EP251118A: 6 GHz VLA Detection
  21. Fermi GRB 251124a: Global MASTER-Net observations report
  22. GRB 251124a: Fermi GBM Final Localization
  23. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  24. EP251124a: GROWTH-India Telescope optical upper limits
  25. GRB 251122A/EP251122a: FTW optical and NIR observations
  26. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  27. The EP-WXT trigger 01709248783 is likely a flaring star
  28. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  29. EP251118A: 3.6m DOT optical afterglow detection
  30. GRB 251122A / EP251122a: EP-FXT counterpart detection
  31. GRB 251122A / EP251122a: WFST optical observations
  32. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  33. GRB 251122A / EP251122a: LCO optical upper limits
  34. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  35. EP251122a: Global MASTER-Net observations report
  36. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  37. GRB 251122A / EP251122a: SVOM detection of a long burst
  38. EP251118a: Continued Optical Detection with Kinder observations
  39. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  40. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  41. EP251118a: Xinglong-2.16m optical observation
  42. GRB 251115A: Fermi GBM Observation
  43. The EP-WXT trigger 01709248635 is likely a flaring star
  44. GRB 251121A: Fermi GBM Final Real-time Localization
  45. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  46. Fermi trigger No 785388351: Global MASTER-Net observations report
  47. EP251118A: 1.3m DFOT optical afterglow detection
  48. GRB 251118A: Swift/UVOT Detection
  49. GRB 251118A: Glowbug gamma-ray detection
  50. GRB 251118A: Fermi GBM Observation
  51. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  52. EP251118a: Optical detection with Kinder observations
  53. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  54. The EP-WXT trigger 01709248403 is likely a flaring star
  55. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  56. GRB 251116C: NOT optical observations
  57. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  58. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  59. GRB 251018A: FRAM-Auger optical detection
  60. The EP-WXT trigger 01709248388 is likely a flaring star
  61. EP251118a: FTW optical and NIR observations
  62. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  63. EP251118a: VLT near-infrared observation
  64. GRB 251116D: SVOM/GRM observation of a long GRB
  65. EP251118a: GOTO optical afterglow detection
  66. GRB 251119A: SVOM detection of a possible burst
  67. EP251118a: Global MASTER-Net observations report
  68. LAT GRB251118.86: Global MASTER-Net observations report
  69. GRB 251118A: Fermi-LAT detection
  70. EP251118a: NOT candidate optical counterpart
  71. EP251118a: Einstein Probe detected of a fast X-ray transient
  72. Fermi GRB 251118B: Global MASTER-Net observations report
  73. GRB 251118B: Fermi GBM Final Real-time Localization
  74. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  75. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  76. GRB 251118A: Fermi GBM Final Real-time Localization
  77. GRB 251116C: SVOM/ECLAIRs refined analysis
  78. GRB 251117A: AstroSat CZTI detection
  79. GRB 251117A: Fermi GBM observation
  80. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  81. GRB 251117A: SVOM/GRM observation of a short burst
  82. GRB 251117A: Fermi-LAT detection
  83. LAT GRB251117.51: Global MASTER-Net observations report
  84. GRB 251116C: Swift/BAT arcminute localization of a burst
  85. GRB 251116B: SVOM/VT optical upper limit
  86. GRB 251116C: Swift-XRT observations
  87. GRB 251117A: Fermi GBM Final Localization Correction
  88. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  89. GRB 251116C: SVOM/VT optical upper limit
  90. GRB 251116B: EP-FXT follow-up observation
  91. GRB 251116B: LCO optical upper limits
  92. GRB 251116C: LCO optical upper limits
  93. SVOM GRB251116C: Global MASTER-Net observations report
  94. GRB 251116C: SVOM detection of a burst
  95. GRB 251116B: SVOM detection of a burst
  96. GRB 251116A: Fermi GBM Final Real-time Localization
  97. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  98. GRB 251115A: Fermi-LAT detection
  99. Fermi GRB 251115A: Global MASTER-Net observations report
  100. GRB 251115A: Fermi GBM Final Real-time Localization

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