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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"

32551 results found.

  1. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  2. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  3. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  4. GRB 250108A: Swift/XRT afterglow fading
  5. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  6. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  7. Konus-Wind detection of GRB 250107C
  8. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  9. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  10. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  11. GRB 250101A: CMO RC-500 optical observations
  12. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  13. EP250108a: EP-FXT follow-up observation
  14. GRB 250109A: Fermi GBM Observation
  15. EP250108a: NOT optical observations
  16. GRB 250109a: GMG Optical Upper Limit
  17. EP250109a: Swift/UVOT non-detection
  18. Konus-Wind detection of GRB 250107D (short/hard)
  19. IPN triangulation of GRB 250107D (short/hard)
  20. IPN triangulation of GRB 250107C
  21. EP250108a: Liverpool Telescope likely optical counterpart
  22. GRB 250108B: Gemini-North likely redshift z = 2.197
  23. GRB 250108B: Swift-BAT refined analysis
  24. GRB 250108B: 1.3m DFOT upper limit
  25. GRB 250108B: REM optical/NIR upper limits
  26. GRB 250109A /EP250109a: Fermi GBM Final Localization
  27. EP250109a: SVOM/VT optical candidate
  28. EP250109a: Global MASTER-Net observations report
  29. GRB 250101A: Terskol K-800 optical observations
  30. EP250109a: GOTO optical upper limits
  31. EP250109a: Swift/XRT non-detection
  32. GRB 250108A: Swift/UVOT Upper Limits
  33. EP250108a: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  35. GRB 250108A: NOT optical upper limit
  36. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  37. Swift GRB 250108B: Global MASTER-Net observations report
  38. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  39. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  40. GRB 250103A: 1.6m Mephisto optical observations
  41. GRB 250108A:SVOM/VT optical candidate
  42. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  43. GRB 250108B: Swift/UVOT Upper Limits
  44. GRB 250108A: Swift ToO observations
  45. GRB 250107A: Fermi GBM Observation
  46. GRB 241228B: Fermi-LAT detection
  47. Fermi GRB 250107B: Global MASTER-Net observations report
  48. GRB 250107A: Swift ToO observations
  49. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  50. GRB 250106A: SVOM/VT 2nd optical deep observation
  51. GRB 250101A: J band upper limit by SYSU 80cm telescope
  52. GRB 250106A: NOT optical observations
  53. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  54. GRB 250103B: REM optical/NIR upper limits
  55. GRB 250101A: REM optical/NIR counterpart detection
  56. GRB 250106A: Swift-XRT observations
  57. GRB 250106A: SVOM/VT optical candidate
  58. GRB 250106A: Swift ToO observations
  59. GRB 241229A: SVOM/VT optical upperlimit
  60. GRB 250103B: LCO/1m optical afterglow candidate detection
  61. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  62. GRB 250103A: Swift-XRT observations
  63. GRB 250101A: 1.3m DFOT optical afterglow detection
  64. GRB 241229A: 1.3m DFOT upper limit
  65. GRB 241228B: 1.3m DFOT Optical observations
  66. GRB 241228A: 1.3m DFOT upper limit
  67. GRB 250103A: NOT spectroscopic redshift
  68. GRB 250103B：SVOM/VT optical counterpart
  69. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  70. GRB 250103A: Montarrenti Observatory optical detection
  71. GRB 250101A: further LCOGT optical afterglow observations
  72. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  73. GRB 250103A: NOT optical observations
  74. GRB 250103A: TSHAO optical upper limit
  75. GRB 250103A: Fermi GBM Observation
  76. GRB 250103B: LCOGT Optical Upper Limit
  77. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  78. Swift GRB 250103B: Global MASTER-Net observations report
  79. GRB 250103A: SVOM/VT optical counterpart confirmation
  80. EP250101a: Liverpool Telescope optical upper limit
  81. GRB 250103A: Swift ToO observations
  82. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 250101a: Liverpool Telescope optical follow-up
  84. GRB 250103B: SVOM detection of a long burst
  85. GRB 250103A: Xinglong 2.16m Optical Candidate
  86. Fermi GRB 250102A: Global MASTER-Net observations report
  87. GRB 250101B: SVOM/GRM observation
  88. GRB 250103A: GOTO optical upper limit
  89. GRB 250103A: SVOM/C-GFT optical upper limit
  90. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  91. EP241231b: optical upper limit with the Liverpool Telescope
  92. EP250101a: Xinglong optical upper limit
  93. GRB 250101A: Swift-BAT refined analysis
  94. GRB 250101A: further SAO RAS optical observations
  95. GRB 250101A: LCO optical counterpart detection
  96. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  97. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  98. GRB 250101A: Swift/UVOT Detection
  99. GRB 250101A: 1.6m Mephisto multi-band optical followup
  100. GRB 250101A: Montarrenti Observatory optical observations and rebrightening

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