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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 251201B: Swift/UVOT Detection
  2. EP251130a: continued NOT optical observations indicate steep fading phase
  3. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  4. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  5. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  6. GRB 251202A: GOTO optical afterglow detection
  7. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  8. GRB 251202A: Swift-XRT afterglow detection
  9. Fermi GRB 251202A: Global MASTER-Net observations report
  10. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  11. Swift GRB 251201B: Global MASTER-Net observations report
  12. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  13. EP251130a: Mondy optical observations
  14. EP251130a: Optical detections with Kinder observations
  15. SVOM GRB251201.19: Global MASTER-Net observations report
  16. EP251130a: SAO RAS optical observations
  17. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  18. EP251130a: KAIT optical observations
  19. EP251130A: Optical observation from 1.3m DFOT
  20. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  21. EP251130a: JinShan optical observations
  22. Fermi GRB 251130B: Global MASTER-Net observations report
  23. IceCube Alert 251130.75: Global MASTER-Net observations report
  24. EP251130a: Swift-XRT counterpart detection
  25. EP251130a: Global MASTER-Net observations report
  26. EP251129a/GRB 251129A: EP-FXT follow-up observations
  27. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  28. GRB 251129A / EP251129a: SAO RAS optical observations
  29. GRB 251126A: SAO RAS optical observations
  30. GRB 251129A: Swift-XRT afterglow detection
  31. GRB 251129A: Swift ToO observations
  32. EP251129a: Global MASTER-Net observations report
  33. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  34. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  35. SVOM GRB251129A: Global MASTER-Net observations report
  36. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  37. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  38. Fermi GRB 251128A: Global MASTER-Net observations report
  39. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  40. GRB 251126A: further SAO RAS optical observations
  41. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  42. GRB 251126A NUTTelA-TAO Early Measurements
  43. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  44. GRB251126A: MAO/AZT-22 optical observations
  45. GRB251126A: Continued optical observation from 1.3m DFOT
  46. GRB 251126A: Swift/UVOT Detection
  47. GRB 251126A: Mondy and SAO RAS optical observations
  48. GRB 251126A: NOT optical observations
  49. GRB 251126A: 1.3m DFOT optical afterglow detection
  50. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  51. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  52. Fermi GRB 251127A: Global MASTER-Net observations report
  53. GRB 251126A: Kilonova-Catcher optical afterglow detection
  54. GRB 251126A: Asiago i-band detection
  55. GRB 251126A: Nanshan/HMT optical afterglow detection
  56. Swift GRB 251126A: Global MASTER-Net observations report
  57. GRB 251126A: GIT discovery of the likely optical afterglow
  58. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  59. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  60. EP251124b: NOT r- and z-band optical upper limits
  61. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  62. Fermi GRB 251125B: Global MASTER-Net observations report
  63. EP251124b: Global MASTER-Net observations report
  64. Fermi GRB 251125A: Global MASTER-Net observations report
  65. EP251124a: NOT r- and z-band optical upper limits
  66. EP251124a: Global MASTER-Net observations report
  67. EP251124a: Swift-XRT observations
  68. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  69. EP251124a: Optical upper limit with Kinder observations
  70. EP251118A: 6 GHz VLA Detection
  71. Fermi GRB 251124a: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  73. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  74. GRB 251116C: Swift-XRT confirmation of fading
  75. GRB 251122A/EP251122a: FTW optical and NIR observations
  76. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  77. EP251118A: 3.6m DOT optical afterglow detection
  78. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  79. GRB 251122A / EP251122a: WFST optical observations
  80. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  81. GRB 251122A / EP251122a: LCO optical upper limits
  82. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  83. EP251122a: Global MASTER-Net observations report
  84. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  85. EP251118a: Continued Optical Detection with Kinder observations
  86. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  87. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  88. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  89. EP251118a: Xinglong-2.16m optical observation
  90. Fermi trigger No 785388351: Global MASTER-Net observations report
  91. EP251118A: 1.3m DFOT optical afterglow detection
  92. GRB 251118A: Swift/UVOT Detection
  93. EP251118a / GRB 251118C: SAO RAS optical observations
  94. GRB 251118A: Swift-XRT afterglow detection
  95. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  96. EP251118a: Optical detection with Kinder observations
  97. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  98. EP251118a / GRB 251118C: SVOM/VT optical observation
  99. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  100. GRB 251116C: NOT optical observations

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