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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"

32716 results found.

  1. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  2. Swift GRB 250108B: Global MASTER-Net observations report
  3. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  4. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  5. GRB 250103A: 1.6m Mephisto optical observations
  6. GRB 250108A:SVOM/VT optical candidate
  7. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  8. GRB 250108B: Swift/UVOT Upper Limits
  9. GRB 250108A: Swift ToO observations
  10. GRB 250107A: Fermi GBM Observation
  11. GRB 241228B: Fermi-LAT detection
  12. Fermi GRB 250107B: Global MASTER-Net observations report
  13. GRB 250107A: Swift ToO observations
  14. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  15. GRB 250106A: SVOM/VT 2nd optical deep observation
  16. GRB 250101A: J band upper limit by SYSU 80cm telescope
  17. GRB 250106A: NOT optical observations
  18. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  19. GRB 250103B: REM optical/NIR upper limits
  20. GRB 250101A: REM optical/NIR counterpart detection
  21. GRB 250106A: Swift-XRT observations
  22. GRB 250106A: SVOM/VT optical candidate
  23. GRB 250106A: Swift ToO observations
  24. GRB 241229A: SVOM/VT optical upperlimit
  25. GRB 250103B: LCO/1m optical afterglow candidate detection
  26. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  27. GRB 250103A: Swift-XRT observations
  28. GRB 250101A: 1.3m DFOT optical afterglow detection
  29. GRB 241229A: 1.3m DFOT upper limit
  30. GRB 241228B: 1.3m DFOT Optical observations
  31. GRB 241228A: 1.3m DFOT upper limit
  32. GRB 250103A: NOT spectroscopic redshift
  33. GRB 250103B：SVOM/VT optical counterpart
  34. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  35. GRB 250103A: Montarrenti Observatory optical detection
  36. GRB 250101A: further LCOGT optical afterglow observations
  37. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  38. GRB 250103A: NOT optical observations
  39. GRB 250103A: TSHAO optical upper limit
  40. GRB 250103A: Fermi GBM Observation
  41. GRB 250103B: LCOGT Optical Upper Limit
  42. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  43. Swift GRB 250103B: Global MASTER-Net observations report
  44. GRB 250103A: SVOM/VT optical counterpart confirmation
  45. EP250101a: Liverpool Telescope optical upper limit
  46. GRB 250103A: Swift ToO observations
  47. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 250101a: Liverpool Telescope optical follow-up
  49. GRB 250103B: SVOM detection of a long burst
  50. GRB 250103A: Xinglong 2.16m Optical Candidate
  51. Fermi GRB 250102A: Global MASTER-Net observations report
  52. GRB 250101B: SVOM/GRM observation
  53. GRB 250103A: GOTO optical upper limit
  54. GRB 250103A: SVOM/C-GFT optical upper limit
  55. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  56. EP241231b: optical upper limit with the Liverpool Telescope
  57. EP250101a: Xinglong optical upper limit
  58. GRB 250101A: Swift-BAT refined analysis
  59. GRB 250101A: further SAO RAS optical observations
  60. GRB 250101A: LCO optical counterpart detection
  61. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  62. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  63. GRB 250101A: Swift/UVOT Detection
  64. GRB 250101A: 1.6m Mephisto multi-band optical followup
  65. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  66. GRB 250101A: LCOGT optical afterglow detection
  67. GRB 250101A: OASDG optical observations
  68. Fermi GRB 250101B: Global MASTER-Net observations report
  69. GRB 250101A: SAO RAS observations of optical brightening
  70. GRB 250101A: AKO Optical Afterglow Detection
  71. GRB 250101A: SAO RAS optical observations
  72. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  73. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  74. GRB 250101A: SVOM/C-GFT early optical observations
  75. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  76. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  77. GRB 250101A: Nanshan/HMT optical observations
  78. GRB 250101A : GIT optical detection
  79. GRB 250101A: GMG Optical Observation
  80. GRB 241217a/EP241217b: ATCA Radio Detection
  81. EP241217a: VLA Radio Detection

  82. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  83. GRB 241229B: Continued CrAO ZTSh observations
  84. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  85. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  86. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  87. GRB 241229A: EP-FXT X-ray afterglow confirmation
  88. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  89. GRB 241229B: SVOM/GRM observation
  90. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  91. EP241217A: J band upper limit by SYSU 80cm telescope
  92. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  93. GRB 241229B: SAO RAS optical upper limit
  94. GRB 241228B: SAO RAS optical observations
  95. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  96. GRB 241229A: SAO RAS optical observations
  97. GRB 241229B: SVOM/VT optical candidate
  98. GRB 241229A: Swift-XRT observations
  99. Konus-Wind detection of GRB 241228A
  100. GRB 241229A: EP-FXT afterglow candidates

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