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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"

25905 results found.

  1. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  2. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  3. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  4. GRB 251126A: further SAO RAS optical observations
  5. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  6. GRB 251126A NUTTelA-TAO Early Measurements
  7. GRB251126A: MAO/AZT-22 optical observations
  8. GRB251126A: Continued optical observation from 1.3m DFOT
  9. GRB 251126A: Swift/UVOT Detection
  10. GRB 251126A: Mondy and SAO RAS optical observations
  11. GRB 251126A: Swift-XRT refined Analysis
  12. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  13. GRB 251126A: NOT optical observations
  14. GRB 251126A: 1.3m DFOT optical afterglow detection
  15. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  16. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  17. GRB 251126A: Enhanced Swift-XRT position
  18. GRB 251126A: Kilonova-Catcher optical afterglow detection
  19. GRB 251126A: Asiago i-band detection
  20. GRB 251126A: Nanshan/HMT optical afterglow detection
  21. Swift GRB 251126A: Global MASTER-Net observations report
  22. GRB 251121A: Fermi GBM Observation
  23. GRB 251126A: Prompt enhanced Swift-XRT position
  24. GRB 251126A: GIT discovery of the likely optical afterglow
  25. GRB 251126A: Swift detection of a burst
  26. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  27. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  28. EP251124a: Xinglong GWAC-F60A optical observation
  29. EP251124a: NOT r- and z-band optical upper limits
  30. EP251124a: Swift-XRT observations
  31. GRB 251116C: Swift-XRT confirmation of fading
  32. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  33. EP251118A: 3.6m DOT optical afterglow detection
  34. GRB 251122A / EP251122a: WFST optical observations
  35. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  36. EP251118a: Xinglong-2.16m optical observation
  37. EP251118A: 1.3m DFOT optical afterglow detection
  38. GRB 251118A: Swift/UVOT Detection
  39. GRB 251118A: Fermi GBM Observation
  40. GRB 251118A: Swift-XRT afterglow detection
  41. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  42. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  43. GRB 251116C: NOT optical observations
  44. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  45. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  46. GRB 251018A: FRAM-Auger optical detection
  47. GRB 251117A: Swift-XRT observations
  48. EP251118a: GOTO optical afterglow detection
  49. EP251118a: NOT spectroscopic redshift of z = 1.216
  50. GRB 251118A: Fermi-LAT detection
  51. EP251118a: NOT candidate optical counterpart
  52. GRB 251118A: Swift ToO observations
  53. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  54. GRB 251116C: SVOM/ECLAIRs refined analysis
  55. GRB 251117A: AstroSat CZTI detection
  56. GRB 251117A: Fermi GBM observation
  57. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  58. GRB 251115A: Swift-XRT observations
  59. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  60. GRB 251117A: Tiled Swift observations
  61. GRB 251117A: Fermi-LAT detection
  62. GRB 251116C: Swift/BAT arcminute localization of a burst
  63. GRB 251116C: Swift-XRT observations
  64. GRB 251116C: SVOM/VT optical upper limit
  65. GRB 251115A: Tiled Swift observations
  66. GRB 251115A: Fermi-LAT detection
  67. GRB 251112A: Swift-BAT refined analysis
  68. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  69. GRB 251112A: Swift/UVOT Upper Limits
  70. GRB 251112A: Swift-XRT refined Analysis
  71. Swift Trigger 1413695: a possible GRB 251112A
  72. GRB251111A: 1.3m DFOT optical upper limit
  73. GRB 251111A: Swift-XRT afterglow detection
  74. GRB 251111A: Swift-XRT observations
  75. GRB 251013C: Chandra X-ray observations and jet break detection
  76. GRB 251111A: KAIT optical upper limit
  77. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  78. GRB 251103B: Swift-BAT refined analysis
  79. GRB 251106A: Swift/UVOT Upper Limits
  80. GRB 251105A: AstroSat CZTI detection
  81. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  82. GRB 251106A: Swift-XRT afterglow detection
  83. GRB 251106A: Kilonova-Catcher optical upper limit
  84. GRB 251106A: Swift/BAT arcminute localization of a burst
  85. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  86. GRB 251103B: AstroSat CZTI detection
  87. GRB 250920C: TERI Gamma-ray detection
  88. GRB 251105A: Fermi GBM Observation
  89. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  90. GRB 251103B: Swift/UVOT Upper Limits
  91. GRB 251103B: Fermi GBM observation
  92. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  93. GRB 251103A: WFST optical observations
  94. EP251102a: OHP/T193 optical observations
  95. GRB 251103A: OHP/T193 optical observations
  96. GRB 251103A: Xinglong 2.16m optical detection
  97. GRB 251103A: KAIT optical observations
  98. GRB 251103B: Nanshan/HMT optical upper limit
  99. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  100. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst

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