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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"

21791 results found.

  1. GRB 251122A/EP251122a: FTW optical and NIR observations
  2. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  3. EP251118A: 3.6m DOT optical afterglow detection
  4. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  5. GRB 251122A / EP251122a: WFST optical observations
  6. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  7. GRB 251122A / EP251122a: LCO optical upper limits
  8. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  9. EP251122a: Global MASTER-Net observations report
  10. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  11. EP251118a: Continued Optical Detection with Kinder observations
  12. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  13. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  14. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  15. EP251118a: Xinglong-2.16m optical observation
  16. Fermi trigger No 785388351: Global MASTER-Net observations report
  17. EP251118A: 1.3m DFOT optical afterglow detection
  18. GRB 251118A: Swift/UVOT Detection
  19. EP251118a / GRB 251118C: SAO RAS optical observations
  20. GRB 251118A: Swift-XRT afterglow detection
  21. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  22. EP251118a: Optical detection with Kinder observations
  23. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  24. EP251118a / GRB 251118C: SVOM/VT optical observation
  25. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  26. GRB 251116C: NOT optical observations
  27. GRB 251117A: Swift-XRT observations
  28. EP251118A / GRB 251118C : MASTER optical counterpart observations
  29. EP251118a: FTW optical and NIR observations
  30. EP251118a: VLT near-infrared observation
  31. EP251118a: GOTO optical afterglow detection
  32. EP251118a: Global MASTER-Net observations report
  33. LAT GRB251118.86: Global MASTER-Net observations report
  34. EP251118a: NOT candidate optical counterpart
  35. GRB 251118A: Swift ToO observations
  36. EP251118a: Einstein Probe detected of a fast X-ray transient
  37. Fermi GRB 251118B: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  39. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  40. GRB 251116C: SVOM/ECLAIRs refined analysis
  41. GRB 251116B: SVOM/ECLAIRs refined analysis
  42. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  43. GRB 251115A: Swift-XRT observations
  44. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  45. GRB 251117A: Tiled Swift observations
  46. LAT GRB251117.51: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  48. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  49. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  50. GRB 251116C: Swift-XRT observations
  51. EP251023a: Assy AZT-20 optical observations
  52. EP251023a: UAFO and AbAO optical observations
  53. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  54. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  55. GRB 251025B: further Mondy optical observations
  56. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  57. SVOM GRB251116C: Global MASTER-Net observations report
  58. GRB 251116B: SVOM detection of a burst
  59. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  60. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  61. GRB 251115A: Tiled Swift observations
  62. Fermi GRB 251115A: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  64. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  65. Fermi trigger No 784717756: Global MASTER-Net observations report
  66. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  67. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  68. Fermi GRB 251114A: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  70. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  71. Fermi GRB 251113A: Global MASTER-Net observations report
  72. GRB 251111A: SVOM/ECLAIRs refined analysis
  73. GRB 251025B: SVOM/ECLAIRs refined analysis
  74. GRB 251112A: Swift/UVOT Upper Limits
  75. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  76. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  77. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  78. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  79. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  80. Fermi trigger No 784621743: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  82. GRB251111A: 1.3m DFOT optical upper limit
  83. GRB 251111A: Swift-XRT afterglow detection
  84. GRB 251111A: SVOM/VT optical observations with X-band data
  85. SVOM GRB251111.42: Global MASTER-Net observations report
  86. GRB 251111A: Swift-XRT observations
  87. SVOM GRB251111.22: Global MASTER-Net observations report
  88. GRB 251013C: Chandra X-ray observations and jet break detection
  89. GRB 251111A: SVOM/VT optical observations with VHF data
  90. GRB 251111A: KAIT optical upper limit
  91. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  92. GRB 251106A: Swift/UVOT Upper Limits
  93. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  94. Fermi trigger No 784329591: Global MASTER-Net observations report
  95. Fermi trigger No 784279167: Global MASTER-Net observations report
  96. SVOM GRB251108.54: Global MASTER-Net observations report
  97. SVOM GRB251106.83: Global MASTER-Net observations report
  98. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  99. GRB 251106A: Swift-XRT afterglow detection
  100. GRB 251106A: Kilonova-Catcher optical upper limit

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