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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"

28132 results found.

  1. GRB 250818A: Swift/UVOT Upper Limits
  2. LIGO/Virgo/KAGRA S250818t: Updated Sky localization
  3. GRB 250818A: Enhanced Swift-XRT position
  4. GRB 250813B: SVOM/ECLAIRs refined analysis
  5. GRB 250818A: Fermi GBM Observation
  6. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  7. GRB 250814A: Further GRAWITA TNG NIR observations
  8. GRB 250818B: Swift-XRT afterglow detection
  9. GRB 250818B: SVOM detection of a short burst
  10. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  11. GRB 250818A: Swift detection of a burst
  12. sb25081602: Swift-XRT observations
  13. GRB 250816A: SVOM/GRM observation of a short burst
  14. GRB 250814A: Swift-BAT refined analysis
  15. GRB 250813B: Liverpool Telescope optical upper limits
  16. GRB 250814A: Further COLIBRÍ optical upper limit
  17. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  18. GRB 250814A: GRAWITA TNG NIR observations
  19. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  20. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  21. GRB250814A: TRT optical upper limits
  22. GRB 250814B: SVOM/GRM observation
  23. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  24. GRB 250813B: SVOM/GRM observation
  25. GRB 250814A: P200/WIRC observations of the afterglow candidate
  26. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  27. GRB 250814A: KAIT optical upper limit
  28. GRB 250814A: Swift-XRT refined Analysis
  29. GRB 240814A: Fermi GBM Observation
  30. GRB 250814A: Possible afterglow candidate from P200/WIRC
  31. GRB 250813B: Fermi GBM Observation
  32. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  33. GRB 250814A: J-band upper limit from WINTER
  34. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 250813B: NOT observations of the optical afterglow
  36. GRB 250814A: COLIBRÍ optical upper limit
  37. GRB 250813A: AstroSat CZTI detection
  38. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  39. GRB 250814A: DDOTI Optical Upper Limit
  40. GRB 250813B: EP-FXT counterpart detection
  41. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  42. GRB 250813B: Swift-XRT afterglow detection
  43. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  44. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  45. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  46. GRB 250813B: SVOM detection of a bright long burst
  47. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  48. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  49. EP250812a: Nickel optical upper limit
  50. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  51. EP250812a: NOT, NTT, and GS observations
  52. GRB 250812A: Swift/UVOT Detection
  53. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  54. EP250812a: Liverpool Telescope upper limits
  55. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  56. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  57. GRB 250812A: EP-FXT counterpart detection
  58. GRB 250807B: Swift-BAT refined analysis
  59. EP 250812a: GOTO optical upper limit
  60. GRB 250812A: Kilonova-Catcher optical afterglow detection
  61. EP250812a: Swift-XRT counterpart detection
  62. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. EP250812a: Einstein Probe detection of an X-ray transient
  64. GRB 250812A: Swift-XRT afterglow detection
  65. GRB 250812A: TRT likely optical counterpart detection
  66. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 250809A: Swift-BAT refined analysis
  68. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  69. GRB 250807A: Swift-BAT refined analysis
  70. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  71. GRB 250809A: Swift/UVOT Detection
  72. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  73. Corrected Swift-XRT Refined Analysis of GRB 250809A
  74. GRB 250809A: Swift-XRT refined Analysis
  75. GRB 250809A: LCOGT Optical Upper Limits
  76. GRB 250808A: VLT X-shooter candidate counterpart
  77. GRB 250809A: Swift detection of a gamma ray burst
  78. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. GRB 250808A: Fermi GBM Observation
  80. GRB 250808A: Swift-XRT candidate counterpart detection
  81. GRB 250807B: Swift/UVOT Detection
  82. GRB 250807B: Kilonova-Catcher optical afterglow detection
  83. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 250807A: Swift/UVOT Detection
  85. GRB 250807A: Swift-XRT refined Analysis
  86. GRB 250806A: SVOM/MXT refined analysis
  87. EP250807a: NTT z-band optical upper limit
  88. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  89. GRB 250807A: SVOM/GRM observation
  90. GRB 250807A: AstroSat CZTI detection of bright long burst
  91. GRB 250807B: Swift-XRT refined Analysis
  92. EP250807a: EP-WXT detection of a fast X-ray transient
  93. EP 250807.979: GOTO optical upper limit
  94. EP250807a: COLIBRÍ optical upper limit
  95. EP250806a: Upper limit from Fermi-GBM Observations
  96. GRB 250807B: Enhanced Swift-XRT position
  97. GRB 250807A: Enhanced Swift-XRT position
  98. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 250807B: Swift detection of a burst with an optical counterpart.
  100. GRB 250805A: Kilonova-Catcher optical upper limits

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