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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"

22216 results found.

  1. GRB 251117A: Swift-XRT observations
  2. EP251118A / GRB 251118C : MASTER optical counterpart observations
  3. EP251118a: FTW optical and NIR observations
  4. EP251118a: VLT near-infrared observation
  5. EP251118a: GOTO optical afterglow detection
  6. GRB 251119A: SVOM detection of a possible burst
  7. EP251118a: Global MASTER-Net observations report
  8. LAT GRB251118.86: Global MASTER-Net observations report
  9. EP251118a: NOT candidate optical counterpart
  10. GRB 251118A: Swift ToO observations
  11. EP251118a: Einstein Probe detected of a fast X-ray transient
  12. Fermi GRB 251118B: Global MASTER-Net observations report
  13. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  14. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  15. GRB 251116C: SVOM/ECLAIRs refined analysis
  16. GRB 251116B: SVOM/ECLAIRs refined analysis
  17. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  18. GRB 251115A: Swift-XRT observations
  19. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  20. GRB 251117A: Tiled Swift observations
  21. LAT GRB251117.51: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  23. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  24. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  25. GRB 251116C: Swift-XRT observations
  26. EP251023a: Assy AZT-20 optical observations
  27. EP251023a: UAFO and AbAO optical observations
  28. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  29. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  30. GRB 251025B: further Mondy optical observations
  31. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  32. SVOM GRB251116C: Global MASTER-Net observations report
  33. GRB 251116B: SVOM detection of a burst
  34. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  35. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  36. GRB 251115A: Tiled Swift observations
  37. Fermi GRB 251115A: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  39. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  40. Konus-Wind detection of GRB 251108C
  41. Fermi trigger No 784717756: Global MASTER-Net observations report
  42. Konus-Wind detection of GRB 251103A
  43. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  44. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  45. Fermi GRB 251114A: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  47. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  48. Fermi GRB 251113A: Global MASTER-Net observations report
  49. GRB 251111A: SVOM/ECLAIRs refined analysis
  50. GRB 251025B: SVOM/ECLAIRs refined analysis
  51. GRB 251112A: Swift/UVOT Upper Limits
  52. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  53. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  54. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  55. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  56. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  57. Fermi trigger No 784621743: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  59. GRB251111A: 1.3m DFOT optical upper limit
  60. GRB 251111A: Swift-XRT afterglow detection
  61. GRB 251111A: SVOM/VT optical observations with X-band data
  62. SVOM GRB251111.42: Global MASTER-Net observations report
  63. GRB 251111A: Swift-XRT observations
  64. SVOM GRB251111.22: Global MASTER-Net observations report
  65. GRB 251013C: Chandra X-ray observations and jet break detection
  66. GRB 251111A: SVOM/VT optical observations with VHF data
  67. GRB 251111A: KAIT optical upper limit
  68. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  69. GRB 251106A: Swift/UVOT Upper Limits
  70. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  71. Fermi trigger No 784329591: Global MASTER-Net observations report
  72. Fermi trigger No 784279167: Global MASTER-Net observations report
  73. SVOM GRB251108.54: Global MASTER-Net observations report
  74. SVOM GRB251106.83: Global MASTER-Net observations report
  75. GRB 251106A: Swift-XRT afterglow detection
  76. GRB 251106A: Kilonova-Catcher optical upper limit
  77. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  78. GRB 251106A: MASTER optical observations
  79. Fermi trigger No 784034269: Global MASTER-Net observations report
  80. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  81. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  82. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 251103B: Swift/UVOT Upper Limits
  84. Fermi GRB 251105A: Global MASTER-Net observations report
  85. EP251102a: FTW optical and NIR observations
  86. GRB 251103A: WFST optical observations
  87. EP251102a: OHP/T193 optical observations
  88. GRB 251103A: OHP/T193 optical observations
  89. GRB 251103A: KAIT optical observations
  90. GRB 251103B: Nanshan/HMT optical upper limit
  91. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  92. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  93. Fermi GRB 251103A: Global MASTER-Net observations report
  94. EP251102a: NIR observations with WINTER
  95. GRB 251103A: J-band detection with WINTER
  96. Swift GRB 251103B: Global MASTER-Net observations report
  97. GRB 251103A: Kilonova-Catcher optical afterglow detection
  98. GRB 251103A: Swift/UVOT Detection
  99. GRB 251103A: Swift-XRT afterglow detection
  100. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations

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