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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').

31191 results found.

  1. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  2. GRB 250103A: 1.6m Mephisto optical observations
  3. GRB 250108A: Swift-XRT afterglow detection
  4. GRB 250108A:SVOM/VT optical candidate
  5. GRB 250108B: Swift/UVOT Upper Limits
  6. GRB 250103A: Swift-XRT afterglow detection
  7. GRB 250108B: Enhanced Swift-XRT position
  8. GRB 250108B: Swift detection of a burst
  9. GRB 250108A: Swift ToO observations
  10. GRB 250108A: SVOM detection of a soft long burst
  11. GRB 250107A: Fermi GBM Observation
  12. GRB 241228B: Fermi-LAT detection
  13. Fermi GRB 250107B: Global MASTER-Net observations report
  14. GRB 250107A: Swift ToO observations
  15. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  16. GRB 250107B: Fermi GBM Final Real-time Localization
  17. GRB 250106A: SVOM/VT 2nd optical deep observation
  18. GRB 250101A: J band upper limit by SYSU 80cm telescope
  19. GRB 250107A: Fermi GBM Final Real-time Localization
  20. GRB 250106A: NOT optical observations
  21. GRB 250103B: REM optical/NIR upper limits
  22. GRB 250101A: REM optical/NIR counterpart detection
  23. GRB 250106A: Swift-XRT observations
  24. GRB 250106A: SVOM/VT optical candidate
  25. GRB 250106A: Swift ToO observations
  26. GRB 250106A: SVOM detection of a long burst
  27. GRB 241229A: SVOM/VT optical upperlimit
  28. GRB 250103B: Swift-XRT refined Analysis
  29. GRB 250103B: LCO/1m optical afterglow candidate detection
  30. GRB 250103A: Bassano Bresciano Observatory upper limit
  31. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  32. GRB 250103A: Swift-XRT observations
  33. GRB 250101A: 1.3m DFOT optical afterglow detection
  34. GRB 241229A: 1.3m DFOT upper limit
  35. GRB 241228B: 1.3m DFOT Optical observations
  36. GRB 241228A: 1.3m DFOT upper limit
  37. GRB 250103A: NOT spectroscopic redshift
  38. GRB 250103B：SVOM/VT optical counterpart
  39. GRB 250103A: Montarrenti Observatory optical detection
  40. GRB 250101A: further LCOGT optical afterglow observations
  41. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  42. GRB 250103A: NOT optical observations
  43. GRB 250103A: TSHAO optical upper limit
  44. GRB 250103A: Fermi GBM Observation
  45. GRB 250103B: LCOGT Optical Upper Limit
  46. Swift GRB 250103B: Global MASTER-Net observations report
  47. GRB 250103A: SVOM/VT optical counterpart confirmation
  48. GRB 250103A: Swift ToO observations
  49. GRB 250101a: Liverpool Telescope optical follow-up
  50. GRB 250103B: SVOM detection of a long burst
  51. GRB 250103B: Swift detection of a burst
  52. GRB 250103A: Xinglong 2.16m Optical Candidate
  53. Fermi GRB 250102A: Global MASTER-Net observations report
  54. GRB 250101B: SVOM/GRM observation
  55. GRB 250103A: GOTO optical upper limit
  56. GRB 250103A: SVOM/C-GFT optical upper limit
  57. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  58. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  59. GRB 250103A: SVOM detection of a long burst
  60. GRB 250102A: Fermi GBM Final Real-time Localization
  61. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  62. GRB 250101A: Swift-BAT refined analysis
  63. GRB 250101A: further SAO RAS optical observations
  64. GRB 250101A: LCO optical counterpart detection
  65. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  66. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  67. GRB 250101A: Swift/UVOT Detection
  68. GRB 250101A: 1.6m Mephisto multi-band optical followup
  69. GRB 250101A: Swift-XRT refined Analysis
  70. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  71. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  72. GRB 250101A: LCOGT optical afterglow detection
  73. GRB 250101A: OASDG optical observations
  74. Fermi GRB 250101B: Global MASTER-Net observations report
  75. GRB 250101B: Fermi GBM Final Real-time Localization
  76. GRB 250101A: SAO RAS observations of optical brightening
  77. GRB 250101A: BOOTES-4/MET optical afterglow detection
  78. GRB 250101A: AKO Optical Afterglow Detection
  79. GRB 250101A: SAO RAS optical observations
  80. GRB 250101A: Enhanced Swift-XRT position
  81. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  82. GRB 250101A: SVOM/C-GFT early optical observations
  83. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  84. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  85. GRB 250101A: Nanshan/HMT optical observations
  86. GRB 250101A : GIT optical detection
  87. GRB 250101A: GMG Optical Observation
  88. GRB 250101A: Swift detection of a burst with an optical counterpart
  89. GRB 241217a/EP241217b: ATCA Radio Detection
  90. GRB 241229B: Continued CrAO ZTSh observations
  91. GRB 241229A: EP-FXT X-ray afterglow confirmation
  92. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  93. GRB 241229B: SVOM/GRM observation
  94. GRB 241229B: SAO RAS optical upper limit
  95. GRB 241228B: SAO RAS optical observations
  96. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  97. GRB 241229A: SAO RAS optical observations
  98. GRB 241229B: SVOM/VT optical candidate
  99. GRB 241229A: Swift-XRT observations
  100. Konus-Wind detection of GRB 241228A

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