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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"

11074 results found.

  1. EP250806a: Einstein Probe detection of an X-ray transient
  2. GRB 250806A: SVOM detection of a soft burst
  3. GRB 250805A: Swift-XRT refined Analysis
  4. GRB 250804C: AstroSat CZTI detection of a long burst
  5. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  6. GRB 250805A: Swift-XRT observations
  7. Swift GRB250805.26: Global MASTER-Net observations report
  8. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  9. The EP-WXT trigger 01709198251 is likely a flaring star
  10. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  11. The EP-WXT trigger 01709198202 is likely a flaring star
  12. EP250711a: CrAO and Assy optical observations
  13. EP250730a: Einstein Probe detection of an X-ray transient
  14. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  15. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  16. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  17. GRB 250725A: AstroSat CZTI detection
  18. Fermi trigger No 775387550: Global MASTER-Net observations report
  19. GRB 250727A: Swift-XRT observations
  20. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  22. The EP-WXT trigger 01709195487 is likely a flaring star
  23. GRB 250725A: Swift-XRT refined Analysis
  24. Konus-Wind detection of GRB 250725A
  25. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  26. GRB 250725A: Fermi-LAT detection
  27. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  28. GRB 250725A: Swift detection of a burst
  29. Fermi GRB 250725A: Global MASTER-Net observations report
  30. Swift GRB 250725A: Global MASTER-Net observations report
  31. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  32. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  33. GRB 250717B: SVOM/GRM observation
  34. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  35. GRB 250721A: MAXI/GSC detection
  36. GRB 250720B: Fermi GBM Final Localization Correction
  37. GRB 250720A: Fermi GBM Final Localization
  38. Fermi trigger No 774730635: Global MASTER-Net observations report
  39. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  40. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  41. GRB 270713A: Kitab and AbAO Optical Observations
  42. Konus-Wind detection of GRB 250716A
  43. GRB 250716A: Swift-XRT afterglow detection
  44. Fermi GRB 250716A: Global MASTER-Net observations report
  45. GRB 250713A: SVOM/C-GFT upper limit
  46. GRB 250713A: Swift-XRT observations
  47. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  48. Fermi GRB 250711A: Global MASTER-Net observations report
  49. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  50. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  51. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  52. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  55. GRB 250704B / EP250704a: VLA radio detection
  56. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  57. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  58. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  59. GRB 250706B/C: Fermi-LAT detection
  60. IceCube-250706A: Global MASTER-Net observations report
  61. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  62. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  63. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  64. GRB 250706B: refined SVOM/MXT data analysis
  65. GRB 250706A: SAO RAS optical observations
  66. GRB250706B: Swift-XRT counterpart detection
  67. GRB 250706B: iTelescope optical observations
  68. GRB 250706B: SVOM detection of a long burst
  69. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  70. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  71. Konus-Wind detection of GRB 250703A
  72. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  73. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  74. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  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. EP250704a / GRB250704B: Swift-XRT counterpart detection
  78. GRB 250704A: Swift-XRT afterglow detection
  79. Konus-Wind detection of GRB 250702F
  80. EP250704a: COLIBRÍ optical counterpart candidate
  81. EP250704a: Einstein Probe detection of an X-ray transient
  82. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  83. GRB 250704A: SVOM detection of a burst
  84. Fermi GRB 250703A: Global MASTER-Net observations report
  85. GRB 250702F: Swift-XRT refined Analysis
  86. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  87. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  88. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  89. EP250702a: Global MASTER-Net observations report
  90. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  91. Fermi GRB 250702C: Global MASTER-Net observations report
  92. Konus-Wind detection of GRB 250627A
  93. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  94. GRB 250628B: Swift-XRT observations
  95. GRB 250628A: REM optical/NIR upper limits
  96. GRB 250628B: SVOM detection of a long burst
  97. GRB 250628A: Swift-XRT refined Analysis
  98. Fermi GRB 250626A: Global MASTER-Net observations report
  99. GRB 250628A: Swift detection of a burst
  100. GRB 250625A: Leavitt Observatory afterglow detection

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