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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"

45664 results found.

  1. GRB 250814B: SVOM/GRM observation
  2. GRB 250814C: SVOM/GRM observation of a short burst
  3. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  4. GRB 250813B: SVOM/GRM observation
  5. GRB 250814A: P200/WIRC observations of the afterglow candidate
  6. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  7. GRB 250814A: KAIT optical upper limit
  8. GRB 250814A: Swift-XRT refined Analysis
  9. GRB 240814A: Fermi GBM Observation
  10. GRB 250814A: Possible afterglow candidate from P200/WIRC
  11. GRB 250813B: Fermi GBM Observation
  12. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  13. Fermi trigger No 776818276: Global MASTER-Net observations report
  14. Swift GRB250814.32: Global MASTER-Net observations report
  15. GRB 250814A: J-band upper limit from WINTER
  16. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 250813B: NOT observations of the optical afterglow
  18. GRB 250813B: SVOM/VT optical observations
  19. Subject GRB 250813B: SVOM/MXT refined analysis
  20. GRB 250814A: COLIBRÍ optical upper limit
  21. GRB 250814B: Fermi GBM Final Real-time Localization
  22. GRB 250813A: AstroSat CZTI detection
  23. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  24. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  25. GRB 250814A: DDOTI Optical Upper Limit
  26. GRB 250813B: EP-FXT counterpart detection
  27. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  28. GRB 250813B: Swift-XRT afterglow detection
  29. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  30. GRB 250814A: Fermi GBM Final Real-time Localization
  31. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  32. GRB 250813B: Ondrejov D50 fast decay
  33. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  34. GRB 250813B: Ondrejov D50 optical afterglow detection
  35. GRB 250813B: SVOM detection of a bright long burst
  36. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  37. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  38. EP250812a: Nickel optical upper limit
  39. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  40. GRB 250812A: NTT spectroscopic redshift z = 2.57
  41. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  42. EP250812a: NOT, NTT, and GS observations
  43. GRB 250812A: Swift/UVOT Detection
  44. GRB 250813A: Fermi GBM Final Localization
  45. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  46. EP250812a: Liverpool Telescope upper limits
  47. EP250812a: SVOM/VT optical counterpart
  48. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  49. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  50. IceCube Alert 250813.14: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  52. GRB 250812A: EP-FXT counterpart detection
  53. GRB 250812A: Swift ToO observations
  54. GRB 250807B: Swift-BAT refined analysis
  55. EP 250812a: GOTO optical upper limit
  56. GRB 250812A: Kilonova-Catcher optical afterglow detection
  57. EP250812a: Swift-XRT counterpart detection
  58. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  59. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  60. EP250812a: Einstein Probe detection of an X-ray transient
  61. GRB 250812A: SVOM/VT optical afterglow confirmation
  62. GRB 250812A: Swift-XRT afterglow detection
  63. GRB 250812A: TRT likely optical counterpart detection
  64. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 250812A: SVOM detection of a faint long burst
  66. GRB 250809A: Swift-BAT refined analysis
  67. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  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 250807B: SVOM/VT optical observation
  76. EP250807a: EP-FXT follow-up observation upper limit
  77. GRB 250809A: LCOGT Optical Upper Limits
  78. GRB 250702B: Chandra X-ray Detection
  79. EP250807a: Global MASTER-Net observations report
  80. Fermi GRB 250808A: Global MASTER-Net observations report
  81. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  82. GRB 250808A: VLT X-shooter candidate counterpart
  83. GRB 250809A: Prompt enhanced Swift-XRT position
  84. GRB 250809A: Swift detection of a gamma ray burst
  85. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB 250808A: Fermi GBM Observation
  87. GRB 250808A: Swift-XRT candidate counterpart detection
  88. GRB 250807A: SVOM/VT optical continued observation
  89. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  90. GRB 250808A: SVOM detection of a long burst
  91. GRB 250808A: Fermi GBM Final Real-time Localization
  92. Konus-Wind detection of GRB 250807A
  93. GRB 250807B: Swift/UVOT Detection
  94. GRB 250807B: Kilonova-Catcher optical afterglow detection
  95. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  96. GRB 250807A: Swift/UVOT Detection
  97. GRB 250807A: Swift-XRT refined Analysis
  98. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  99. GRB 250806A: SVOM/MXT refined analysis
  100. GRB 250806A: SVOM/ECLAIRs refined analysis

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