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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"

32721 results found.

  1. GRB 250818B: Swift/UVOT Detection
  2. LIGO/Virgo/KAGRA S250818k: FTW Fast reddening of AT 2025ulz
  3. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  4. GRB 250818B: TRT Optical Observation
  5. Fermi GRB 250816A: Global MASTER-Net observations report
  6. GRB 250818B: SAO RAS optical observations
  7. Swift GRB 250818A: Global MASTER-Net observations report
  8. GRB 250818B: NOT optical observations
  9. GRB 250818B: EP-FXT counterpart detection
  10. GRB 250818A: Swift-BAT refined analysis
  11. LIGO/Virgo/KAGRA S250818k: FTW optical and NIR observations of AT 2025ulz
  12. GRB 250818B: Keck redshift of the optical afterglow
  13. GRB 250818B: KAIT optical observations
  14. GRB 250818A: Swift/UVOT Upper Limits
  15. LIGO/Virgo/KAGRA S250818t: Updated Sky localization
  16. GRB 250813B: SVOM/ECLAIRs refined analysis
  17. GRB 250818A: Fermi GBM Observation
  18. GRB 250818B: SVOM/VT optical observation
  19. GRB 250814A: Further GRAWITA TNG NIR observations
  20. GRB 250818B: Swift-XRT afterglow detection
  21. GRB 250818B: GOTO optical counterpart candidate
  22. GRB 250818B: SVOM detection of a short burst
  23. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  24. sb25081602: Swift-XRT observations
  25. GRB 250816A: SVOM/GRM observation of a short burst
  26. Fermi GRB 250814B: Global MASTER-Net observations report
  27. GRB 250814A: Swift-BAT refined analysis
  28. GRB 250813B: Liverpool Telescope optical upper limits
  29. GRB 250814A: Further COLIBRÍ optical upper limit
  30. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  31. GRB 250814A: GRAWITA TNG NIR observations
  32. GRB 250812A: SVOM/VT optical continued observation
  33. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  34. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  35. GRB250814A: TRT optical upper limits
  36. GRB 250814B: SVOM/GRM observation
  37. GRB 250813B: SVOM/GRM observation
  38. GRB 250814A: P200/WIRC observations of the afterglow candidate
  39. GRB 250814A: KAIT optical upper limit
  40. GRB 240814A: Fermi GBM Observation
  41. GRB 250814A: Possible afterglow candidate from P200/WIRC
  42. GRB 250813B: Fermi GBM Observation
  43. GRB 250814A: J-band upper limit from WINTER
  44. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 250813B: NOT observations of the optical afterglow
  46. GRB 250813B: SVOM/VT optical observations
  47. Subject GRB 250813B: SVOM/MXT refined analysis
  48. GRB 250814A: COLIBRÍ optical upper limit
  49. GRB 250813A: AstroSat CZTI detection
  50. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  51. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  52. GRB 250814A: DDOTI Optical Upper Limit
  53. GRB 250813B: EP-FXT counterpart detection
  54. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  55. GRB 250813B: Swift-XRT afterglow detection
  56. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  57. GRB 250813B: Ondrejov D50 fast decay
  58. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  59. GRB 250813B: Ondrejov D50 optical afterglow detection
  60. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  61. EP250812a: Nickel optical upper limit
  62. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  63. GRB 250812A: NTT spectroscopic redshift z = 2.57
  64. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  65. EP250812a: NOT, NTT, and GS observations
  66. GRB 250812A: Swift/UVOT Detection
  67. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  68. EP250812a: Liverpool Telescope upper limits
  69. EP250812a: SVOM/VT optical counterpart
  70. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  71. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  72. GRB 250812A: EP-FXT counterpart detection
  73. GRB 250812A: Swift ToO observations
  74. GRB 250807B: Swift-BAT refined analysis
  75. EP 250812a: GOTO optical upper limit
  76. GRB 250812A: Kilonova-Catcher optical afterglow detection
  77. EP250812a: Swift-XRT counterpart detection
  78. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. GRB 250812A: SVOM/VT optical afterglow confirmation
  80. GRB 250812A: TRT likely optical counterpart detection
  81. GRB 250809A: Swift-BAT refined analysis
  82. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  83. GRB 250807A: Swift-BAT refined analysis
  84. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  85. GRB 250809A: Swift/UVOT Detection
  86. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  87. Corrected Swift-XRT Refined Analysis of GRB 250809A
  88. GRB 250807B: SVOM/VT optical observation
  89. EP250807a: EP-FXT follow-up observation upper limit
  90. GRB 250809A: LCOGT Optical Upper Limits
  91. GRB 250702B: Chandra X-ray Detection
  92. EP250807a: Global MASTER-Net observations report
  93. Fermi GRB 250808A: Global MASTER-Net observations report
  94. GRB 250808A: VLT X-shooter candidate counterpart
  95. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 250808A: Fermi GBM Observation
  97. GRB 250807A: SVOM/VT optical continued observation
  98. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  99. GRB 250808A: SVOM detection of a long burst
  100. Konus-Wind detection of GRB 250807A

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