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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"

2409 results found.

  1. GRB 251222A: 1.3m DFOT optical detection
  2. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  3. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  4. EP251222b/GRB 251222A: SVOM/GRM observation
  5. GRB 251222A: PRIME near-infrared detection
  6. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  7. IPN triangulation of GRB 251220B (short)
  8. GRB 251222A: Swift ToO observations
  9. GRB 251222A: SVOM/VT optical candidate
  10. GRB 251222A: SVOM detection of a long burst
  11. SVOM GRB251222A: Global MASTER-Net observations report
  12. GRB 251220B: SVOM/GRM observation of a short burst
  13. SVOM GRB251220.98: Global MASTER-Net observations report
  14. GRB 251219A: SVOM/GRM observation of a short burst
  15. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  16. SVOM GRB251219.11: Global MASTER-Net observations report
  17. GRB 251213A: GRID-10B observation
  18. GRB 251202A: radio detection with the VLA
  19. GRB 251214D: GECAM-B observation of a long burst
  20. GRID detection of GRB 251213A
  21. GRB 251214B: GECAM-B observation of a long burst
  22. GRB 251213A: SVOM/GRM observation
  23. GRB 251213A: GECAM-B detection
  24. GRB 251214A: GECAM-B observation of a likely long burst
  25. GRB 251214B : MASTER optical afterglow detection
  26. GRB 251214B: SVOM/C-GFT optical observations
  27. SVOM GRB251211.12: Global MASTER-Net observations report
  28. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  29. GRB 251208A: AstroSat CZTI detection
  30. GRB 251208A: Glowbug gamma-ray detection
  31. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  32. GRB 251208C: GECAM-B observation of a short burst
  33. GRB 251208A: GECAM-B observation of a short burst
  34. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. GRB 251208D: LAST optical upper limit
  36. GRB 251208D: LCO analysis of the XRT sources
  37. GRB 251208D: Swift-XRT observations
  38. GRB 251208A: SVOM/GRM observation of a short burst
  39. GRB 251208C: SVOM/GRM observation of a short burst
  40. GRB 251208D: LCO optical upper limits
  41. SVOM GRB251208D: Global MASTER-Net observations report
  42. GRB 251208D: SVOM possible detection of a faint burst
  43. GRB 251206A: SVOM detection of a burst through offline search
  44. SVOM GRB251206.86: Global MASTER-Net observations report
  45. GRB 251203C: Swift/UVOT Upper Limit
  46. GRB 251203A: Insight-HXMT/HE detection
  47. GRB 251203C: SVOM/ECLAIRs refined analysis
  48. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  49. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  50. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. GRB 251202A: SVOM/GRM observation
  52. GRB 251203A: GECAM-B observation of a burst
  53. GRB 251203A: SVOM/GRM observation
  54. GRB 251203C: LCO optical afterglow confirmation
  55. GRB 251203C: SVOM/VT optical counterpart
  56. GRB 251203C: EP-FXT follow-up observation
  57. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  58. GRB 251203B: Swift-XRT observations
  59. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  60. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  61. GRB 251203C: LCO optical upper limits
  62. GRB 251203B: LCO optical upper limits
  63. GRB 251203B: SVOM/VT optical observation
  64. GRB 251203C: SVOM detection of a burst
  65. SVOM GRB251203.77: Global MASTER-Net observations report
  66. SVOM GRB251203B: Global MASTER-Net observations report
  67. GRB 251203B: SVOM detection of a burst
  68. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  69. GRB 251202A / EP251202a: SVOM/VT optical observation
  70. GRB251129A/EP251129a: Swift UVOT detection
  71. GRB 251201B: Kilonova-Catcher optical afterglow detection
  72. GRB 251201A: GECAM-B observation of a burst
  73. GRB 251126A: SVOM/VT optical observation
  74. EP251130a: SVOM/VT optical observation
  75. GRB 251201A: SVOM/GRM observation of a burst
  76. GRB 251201B: SVOM/VT optical fading
  77. SVOM GRB251201.19: Global MASTER-Net observations report
  78. GRB 251127A: SVOM/GRM observation
  79. EP251129a/GRB 251129A: EP-FXT follow-up observations
  80. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  81. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  82. GRB 251129A / EP251129a: SAO RAS optical observations
  83. GRB 251128A: SVOM/GRM observation of a long burst
  84. SVOM GRB 251129A : MASTER optical counterpart detection
  85. GRB 251129A: Swift-XRT afterglow detection
  86. GRB 251129A: Swift ToO observations
  87. GRB 251129A / EP251129a: SVOM/VT optical fading
  88. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  89. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  90. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  91. GRB 251129A: SVOM detection of a burst
  92. SVOM GRB251129A: Global MASTER-Net observations report
  93. GRB 251129A: SVOM detection of a burst
  94. EP251124a: Xinglong GWAC-F60A optical observation
  95. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  96. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  97. GRB 251116C: Swift-XRT confirmation of fading
  98. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  99. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  100. GRB 251122A / EP251122a: EP-FXT counterpart detection

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