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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"

20500 results found.

  1. EP250404a: BOOTES-4/JGT optical afterglow detection
  2. EP250404a: Nanshan/HMT optical counterpart detection
  3. EP250404a: Einstein Probe detection of an X-ray transient
  4. GRB 250404A: Fermi GBM Final Real-time Localization
  5. GRB 250403A: Swift/UVOT Detection
  6. GRB 250402A: Swift/UVOT Upper Limits
  7. EP250402a: Optical upper limit with Kinder observations
  8. GRB 250403A: REM NIR afterglow detection
  9. GRB 250403A: LCO optical counterpart detection
  10. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  11. GRB 250403A: JinShan optical observations
  12. GRB 250403A: Optical counterpart detection by LCO.
  13. GRB 250322A: 10 GHz VLA radio upper limits
  14. GRB 250402A: NUTTelA-TAO Early Optical Limits
  15. GRB 250403A: GMG Optical Observation
  16. GRB 250403A: 1.6m Mephisto multi-band optical detection
  17. GRB 250403A: SVOM/C-GFT optical observations
  18. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  19. GRB 250402A: REM optical/NIR upper limits
  20. GRB 250402A: LCO optical counterpart detection
  21. EP250402a: Einstein Probe detection of a fast X-ray transient
  22. GRB 250402A: SVOM/VT optical counterpart
  23. GRB 250402A: SVOM detection of a burst
  24. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  25. GRB 250329B: Swift/UVOT Upper Limit
  26. GRB 250329A: Swift/UVOT Upper Limit
  27. GRB 250327B: Swift/UVOT Detection
  28. GRB 250327A: Swift/UVOT Upper Limits
  29. GRB 250331E: SVOM/GRM observation
  30. GRB 250327B: Kilonova-Catcher Observations
  31. GRB250331D: AbAO optical observations
  32. GRB 250331C: Swift/UVOT Upper Limits
  33. GRB 250331B: Swift/UVOT Upper Limits
  34. GRB 250328A: AbAO AS-32 Optical Observations
  35. GRB 250219A: NOT candidate host galaxy detection
  36. GRB 250331D: Swift-XRT observations
  37. GRB 250331B: Swift-XRT refined Analysis
  38. GRB 250331B: Swift-XRT refined Analysis
  39. GRB 250330B: SVOM/GRM observation of a short burst
  40. Fermi GRB 250331E: Global MASTER-Net observations report
  41. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  42. GRB 250331C: Enhanced Swift-XRT position
  43. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  44. GRB 250331B: Enhanced Swift-XRT position
  45. GRB 250320C : SVOM detection of a burst through offline search
  46. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  47. GRB 250330A: VLT/FORS2 Afterglow Detection
  48. GRB20250327B: 45th Parallel Observatory upper limit
  49. GRB 250328A: Swift/UVOT Detection
  50. GRB 250328A: Swift-XRT refined Analysis
  51. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  52. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  53. GRB 250331C: Swift detection of a burst
  54. GRB 250331B: Swift detection of a burst
  55. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  56. GRB 250330A: Swift/UVOT Upper Limits
  57. GRB 250330A: Swift-XRT afterglow detection
  58. GRB 250328A: 1.6m Mephisto optical observations
  59. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  60. GRB 250330A: VLT/FORS2 Optical Observations
  61. GRB 250330A: Prompt Swift-XRT position
  62. GRB 250329B: Swift-XRT afterglow detection
  63. GRB 250330A: Swift detection of a burst
  64. GRB 250329B: SVOM/C-GFT optical upper limit
  65. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  66. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  67. GRB250329A: REM optical afterglow detection
  68. GRB 250329B: GWAC-F50A optical upper limit
  69. GRB 250329A: Swift-XRT afterglow detection
  70. GRB 250328A: SVOM/VT optical observation
  71. GRB 250329A: Fading optical counterpart detection by LCO.
  72. GRB 250328A: SVOM/C-GFT optical upper limit
  73. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  74. GRB 250329A: VLT/X-shooter redshift z = 2.921
  75. GRB 250329A: SVOM/VT optical counterpart confirmation
  76. GRB 250329A: SVOM detection of a burst
  77. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  78. GRB 250327B: J-band observations with WINTER
  79. GRB 250327B: LCO optical counterpart detection
  80. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  81. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  82. GRB 250327B: CrAO and SAO RAS Optical Observations
  83. EP250315a: Pan-STARRS r and i-band imaging and photometry
  84. GRB 250327b: Liverpool Telescope optical observations
  85. GRB 250322A: GRANDMA/TNOT optical upper limits
  86. GRB 250327A: SVOM/VT upper limits on the XRT position
  87. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  88. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  89. GRB 250327B: Las Cumbres optical counterpart detection
  90. GRB 250327B: 1.6m Mephisto optical observations
  91. GRB 250327B: NOT spectroscopic redshift z = 3.035
  92. GRB 250327B: SVOM/VT optically bright counterpart
  93. GRB 250327B: SAO RAS optical candidate
  94. GRB 250327B: SVOM detection of a burst
  95. GRB 250327A: J-band observations with WINTER
  96. GRB 250327A: SVOM/VT optical candidate
  97. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  98. GRB 250327A: DDOTI Optical Observations
  99. GRB 250327A: COLIBRÍ optical upper limit
  100. IPN triangulation of GRB 250322B

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