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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"

28233 results found.

  1. GRB 250818B: KAIT optical observations
  2. GRB 250818A: Swift/UVOT Upper Limits
  3. LIGO/Virgo/KAGRA S250818t: Updated Sky localization
  4. GRB 250818A: Enhanced Swift-XRT position
  5. GRB 250813B: SVOM/ECLAIRs refined analysis
  6. GRB 250818A: Fermi GBM Observation
  7. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  8. GRB 250814A: Further GRAWITA TNG NIR observations
  9. GRB 250818B: Swift-XRT afterglow detection
  10. GRB 250818B: SVOM detection of a short burst
  11. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  12. GRB 250818A: Swift detection of a burst
  13. sb25081602: Swift-XRT observations
  14. GRB 250816A: SVOM/GRM observation of a short burst
  15. GRB 250814A: Swift-BAT refined analysis
  16. GRB 250813B: Liverpool Telescope optical upper limits
  17. GRB 250814A: Further COLIBRÍ optical upper limit
  18. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  19. GRB 250814A: GRAWITA TNG NIR observations
  20. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  21. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  22. GRB250814A: TRT optical upper limits
  23. GRB 250814B: SVOM/GRM observation
  24. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  25. GRB 250813B: SVOM/GRM observation
  26. GRB 250814A: P200/WIRC observations of the afterglow candidate
  27. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  28. GRB 250814A: KAIT optical upper limit
  29. GRB 250814A: Swift-XRT refined Analysis
  30. GRB 240814A: Fermi GBM Observation
  31. GRB 250814A: Possible afterglow candidate from P200/WIRC
  32. GRB 250813B: Fermi GBM Observation
  33. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  34. GRB 250814A: J-band upper limit from WINTER
  35. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 250813B: NOT observations of the optical afterglow
  37. GRB 250814A: COLIBRÍ optical upper limit
  38. GRB 250813A: AstroSat CZTI detection
  39. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  40. GRB 250814A: DDOTI Optical Upper Limit
  41. GRB 250813B: EP-FXT counterpart detection
  42. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  43. GRB 250813B: Swift-XRT afterglow detection
  44. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  45. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  46. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  47. GRB 250813B: SVOM detection of a bright long burst
  48. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  49. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  50. EP250812a: Nickel optical upper limit
  51. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  52. EP250812a: NOT, NTT, and GS observations
  53. GRB 250812A: Swift/UVOT Detection
  54. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  55. EP250812a: Liverpool Telescope upper limits
  56. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  57. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  58. GRB 250812A: EP-FXT counterpart detection
  59. GRB 250807B: Swift-BAT refined analysis
  60. EP 250812a: GOTO optical upper limit
  61. GRB 250812A: Kilonova-Catcher optical afterglow detection
  62. EP250812a: Swift-XRT counterpart detection
  63. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  64. EP250812a: Einstein Probe detection of an X-ray transient
  65. GRB 250812A: Swift-XRT afterglow detection
  66. GRB 250812A: TRT likely optical counterpart detection
  67. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  68. GRB 250809A: Swift-BAT refined analysis
  69. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  70. GRB 250807A: Swift-BAT refined analysis
  71. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  72. GRB 250809A: Swift/UVOT Detection
  73. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  74. Corrected Swift-XRT Refined Analysis of GRB 250809A
  75. GRB 250809A: Swift-XRT refined Analysis
  76. GRB 250809A: LCOGT Optical Upper Limits
  77. GRB 250808A: VLT X-shooter candidate counterpart
  78. GRB 250809A: Swift detection of a gamma ray burst
  79. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  80. GRB 250808A: Fermi GBM Observation
  81. GRB 250808A: Swift-XRT candidate counterpart detection
  82. GRB 250807B: Swift/UVOT Detection
  83. GRB 250807B: Kilonova-Catcher optical afterglow detection
  84. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  85. GRB 250807A: Swift/UVOT Detection
  86. GRB 250807A: Swift-XRT refined Analysis
  87. GRB 250806A: SVOM/MXT refined analysis
  88. EP250807a: NTT z-band optical upper limit
  89. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  90. GRB 250807A: SVOM/GRM observation
  91. GRB 250807A: AstroSat CZTI detection of bright long burst
  92. GRB 250807B: Swift-XRT refined Analysis
  93. EP250807a: EP-WXT detection of a fast X-ray transient
  94. EP 250807.979: GOTO optical upper limit
  95. EP250807a: COLIBRÍ optical upper limit
  96. EP250806a: Upper limit from Fermi-GBM Observations
  97. GRB 250807B: Enhanced Swift-XRT position
  98. GRB 250807A: Enhanced Swift-XRT position
  99. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 250807B: Swift detection of a burst with an optical counterpart.

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