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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

25006 results found.

  1. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  2. GRB 250704A: GRANDMA observations
  3. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  4. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  6. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  7. IceCube-250708A: No Candidates from WINTER
  8. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  9. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  10. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  11. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  12. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  13. EP250704a/GRB 250704B: 10 GHz VLA detection
  14. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  15. IceCube-250706A: No Candidates from WINTER
  16. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  17. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  18. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  19. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  20. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  21. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  22. EP250704a/GRB250704B : HCT optical and NIR upper limits
  23. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  24. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  25. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  26. GRB 250702F: radio detection with the VLA
  27. IceCube-250706A: EP-FXT follow-up observations
  28. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  29. GRB 250706B/C: Fermi-LAT detection
  30. IceCube-250706A: Global MASTER-Net observations report
  31. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  32. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  33. GRB 250706B: Swift/UVOT Detection
  34. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  35. GRB 250702F: GRANDMA observations
  36. GRB 250706A: Swift-XRT refined Analysis
  37. GRB 250706B: refined SVOM/MXT data analysis
  38. GRB 250706A: Swift/UVOT Upper Limits
  39. GRB 250706B: REM optical observations
  40. GRB 250706A: REM optical/NIR observations
  41. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  42. IceCube-250416A: DDOTI Optical Upper Limit
  43. IceCube-250706A: COLIBRÍ optical upper limits
  44. GRB 250706A: JinShan optical upper limits
  45. GRB 250706A: SAO RAS optical observations
  46. EP250704A: NOWT Detection
  47. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  48. GRB250706B: Swift-XRT counterpart detection
  49. GRB 250706B: iTelescope optical observations
  50. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  51. GRB 250706B: SVOM/VT optical observation
  52. GRB 250706B: TRT bright optical counterpart detection
  53. GRB 250706A: GROWTH-India Telescope optical upper limit
  54. GRB 250706B: SVOM detection of a long burst
  55. GRB 250706A: Swift detection of a burst
  56. GRB 250704B: Swift-XRT refined Analysis
  57. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  58. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  59. GRB 250703A: EIRSAT-1 GMOD Detection
  60. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  61. GRB 250704B: Swift/UVOT Upper Limits
  62. GRB 250704A: Swift/UVOT Detection
  63. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  64. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  65. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  66. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  67. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  68. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  69. GRB 250702F: Kilonova-Catcher optical afterglow detection
  70. GRB 250702F: Monte Agliale Observatory optical observations
  71. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  72. EP250704a / GRB 250704B: JinShan optical observations
  73. EP250704a / GRB 250704B: SAO RAS optical observations
  74. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  75. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  76. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  77. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  78. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  79. EP250704a / GRB250704B: Swift-XRT counterpart detection
  80. GRB 250704A: Swift-XRT afterglow detection
  81. EP250704a / GRB 250704B - REM observations
  82. GRB 250702F: GROWTH-India Telescope optical observations
  83. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  84. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  85. EP250702a: WFST optical observations
  86. EP250704a: COLIBRÍ optical counterpart candidate
  87. EP250704a: Einstein Probe detection of an X-ray transient
  88. GRB 250704A: REM detection of the optical afterglow
  89. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  90. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  91. GRB 250704A: SVOM detection of a burst
  92. GRB 250702F: Swift/UVOT Detection
  93. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  94. GRB 250702F: Swift-XRT refined Analysis
  95. GRB 250702F: Fermi GBM Observation
  96. GRB 250702F: Leavitt Observatory optical observations
  97. GRB 250702F: AKO Optical Afterglow Detection
  98. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  99. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  100. GRB 250702F: Skynet Optical Observations

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