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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"

2410 results found.

  1. GRB 251028A: GECAM-B detection
  2. GRB 251028A: SVOM/GRM observation
  3. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  4. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  5. GRB251025B: 3.6m DOT Optical Observations
  6. SVOM trigger sb25102702/GRB 251027A is not a GRB
  7. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  8. Konus-Wind detection of GRB 251022A
  9. GRB 251027A: Swift-XRT observations
  10. GRB 251022A: SVOM/GRM observation
  11. GRB 251027A: LCO optical upper limit
  12. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. GRB 251026A: Mondy optical upper limit
  14. GRB 251025B: Kilonova-Catcher optical afterglow detection
  15. Konus-Wind detection of GRB 251016A (short/hard)
  16. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  17. GRB 251027A: SVOM detection of a faint burst
  18. GRB 251026A: Swift-XRT observations
  19. GRB 251026A: SVOM/C-GFT upper limit
  20. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. GRB 251026A: SVOM detection of a long burst
  22. GRB 251025B: SVOM/VT optical bump
  23. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  24. GRB 251023A: SVOM/GRM observation
  25. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  26. GRB 251025B: GROWTH-India Telescope optical observations
  27. GRB 251025B: Swift-XRT afterglow detection
  28. GRB 251025A (sb25102501): stellar flare confirmed
  29. GRB 251025B: SVOM/VT optical observations with VHF data
  30. GRB 251025B: MASTER OT detection
  31. GRB 251025B: SVOM/C-GFT optical counterpart detection
  32. GRB 251025B: SVOM detection of a burst
  33. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  34. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. GRB 251025A: SVOM/VT VHF optical upper limit
  36. GRB 251025A: SVOM detection of a faint burst
  37. EP251021b/GRB 251021A: SVOM/VT optical candidate
  38. GRB 251016A: SVOM/ECLAIRs refined analysis
  39. GRB 251016A: Fermi GBM Observation
  40. GRB 251016A: HXMT/HE detection
  41. GRB 251016A: Swift-XRT afterglow detection
  42. GRB 251016A: Swift/UVOT Detection
  43. GRB 251016A: VLT/FORS2 Optical Observation
  44. GRB 251017A: SVOM/VT optical observation
  45. GRB 251016A: AstroSat CZTI detection of a short burst
  46. GRB 251017A: COLIBRÍ Early Afterglow Detection
  47. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  49. GRB 251016A: BOOTES-6/DPRT optical upper limit
  50. GRB 251016A: Glowbug gamma-ray detection of a short burst
  51. sb25101602: Swift-XRT counterpart detection
  52. GRB 251016A: SVOM detection of a short burst
  53. GRB 251013C: Kilonova-Catcher optical afterglow detection
  54. GRB 251013C: Swift/UVOT Detection
  55. Konus-Wind detection of GRB 251007A
  56. GRB 251013C: SVOM/ECLAIRs refined analysis
  57. GRB 251011B: SVOM/VT optical upper limit
  58. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  59. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  60. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  61. GRB 251013C: MarSEC, optical afterglow photometry
  62. GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
  63. GRB 251013C: Bassano Bresciano Observatory optical observations
  64. GRB 251013C: Early and late-time optical counterpart detection by LCO
  65. GRB 251013C: Fermi GBM Observation
  66. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  67. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  68. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  69. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  70. GRB 251013C: EP-FXT counterpart detection
  71. GRB 251013C: AstroSat CZTI detection
  72. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  73. GRB 251013C: DDOTI detection of the optical afterglow
  74. GRB 251013C: SLKT optical afterglow photometry
  75. GRB 251013C: Swift-XRT counterpart detection
  76. GRB 251013C: LCO optical afterglow detection
  77. GRB 251013C: LAST detection of optical counterpart
  78. GRB 251013C: BOOTES-6 early optical detection
  79. GRB 251013C: SVOM/VT optical observation
  80. GRB 251013C: SVOM detection of a burst
  81. GRB 251013B: SVOM/GRM observation
  82. GRB 251013A: SVOM/GRM observation
  83. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  84. GRB 251011B: SVOM/GRM observation
  85. GRB 251009B: SVOM/GRM observation of short GRB
  86. GRB 251009A: GECAM-B detection of a short burst
  87. GRB 251009A: Insight-HXMT detection of a short burst
  88. GRB 251009B: Insight-HXMT detection of a short burst
  89. GRB 251009A: SVOM/GRM observation of short GRB with possible tail emission
  90. GRB 251007A: SVOM/GRM observation
  91. GRB 251007B - SVOM/ECLAIRs refined analysis
  92. SVOM/sb25101004: SVOM detection of a stellar flare
  93. GRB 250919A: TERI gamma-ray detection
  94. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  95. GRB 251002A - SVOM/ECLAIRs refined analysis
  96. GRB 251006B: Fermi GBM Observation
  97. GRB 251007B: COLIBRÍ optical upper limit
  98. GRB 251006B/EP251006a: EP-FXT afterglow detection
  99. GRB 251007B: SVOM/VT optical candidate
  100. GRB 251007A: NOT optical observations

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