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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"

31633 results found.

  1. IPN triangulation of GRB 250107C
  2. EP250108a: Liverpool Telescope likely optical counterpart
  3. GRB 250108B: Gemini-North likely redshift z = 2.197
  4. GRB 250108B: Swift-BAT refined analysis
  5. GRB 250108B: 1.3m DFOT upper limit
  6. GRB 250108B: REM optical/NIR upper limits
  7. GRB 250109A /EP250109a: Fermi GBM Final Localization
  8. EP250109a: SVOM/VT optical candidate
  9. EP250109a: Global MASTER-Net observations report
  10. GRB 250101A: Terskol K-800 optical observations
  11. EP250109a: GOTO optical upper limits
  12. EP250109a: Swift/XRT non-detection
  13. GRB 250108A: Swift/UVOT Upper Limits
  14. EP250108a: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  16. GRB 250108A: NOT optical upper limit
  17. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  18. Swift GRB 250108B: Global MASTER-Net observations report
  19. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  20. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  21. GRB 250103A: 1.6m Mephisto optical observations
  22. GRB 250108A:SVOM/VT optical candidate
  23. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  24. GRB 250108B: Swift/UVOT Upper Limits
  25. GRB 250108A: Swift ToO observations
  26. GRB 250107A: Fermi GBM Observation
  27. GRB 241228B: Fermi-LAT detection
  28. Fermi GRB 250107B: Global MASTER-Net observations report
  29. GRB 250107A: Swift ToO observations
  30. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  31. GRB 250106A: SVOM/VT 2nd optical deep observation
  32. GRB 250101A: J band upper limit by SYSU 80cm telescope
  33. GRB 250106A: NOT optical observations
  34. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  35. GRB 250103B: REM optical/NIR upper limits
  36. GRB 250101A: REM optical/NIR counterpart detection
  37. GRB 250106A: Swift-XRT observations
  38. GRB 250106A: SVOM/VT optical candidate
  39. GRB 250106A: Swift ToO observations
  40. GRB 241229A: SVOM/VT optical upperlimit
  41. GRB 250103B: LCO/1m optical afterglow candidate detection
  42. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  43. GRB 250103A: Swift-XRT observations
  44. GRB 250101A: 1.3m DFOT optical afterglow detection
  45. GRB 241229A: 1.3m DFOT upper limit
  46. GRB 241228B: 1.3m DFOT Optical observations
  47. GRB 241228A: 1.3m DFOT upper limit
  48. GRB 250103A: NOT spectroscopic redshift
  49. GRB 250103B：SVOM/VT optical counterpart
  50. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  51. GRB 250103A: Montarrenti Observatory optical detection
  52. GRB 250101A: further LCOGT optical afterglow observations
  53. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  54. GRB 250103A: NOT optical observations
  55. GRB 250103A: TSHAO optical upper limit
  56. GRB 250103A: Fermi GBM Observation
  57. GRB 250103B: LCOGT Optical Upper Limit
  58. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  59. Swift GRB 250103B: Global MASTER-Net observations report
  60. GRB 250103A: SVOM/VT optical counterpart confirmation
  61. EP250101a: Liverpool Telescope optical upper limit
  62. GRB 250103A: Swift ToO observations
  63. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 250101a: Liverpool Telescope optical follow-up
  65. GRB 250103B: SVOM detection of a long burst
  66. GRB 250103A: Xinglong 2.16m Optical Candidate
  67. Fermi GRB 250102A: Global MASTER-Net observations report
  68. GRB 250101B: SVOM/GRM observation
  69. GRB 250103A: GOTO optical upper limit
  70. GRB 250103A: SVOM/C-GFT optical upper limit
  71. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  72. EP241231b: optical upper limit with the Liverpool Telescope
  73. EP250101a: Xinglong optical upper limit
  74. GRB 250101A: Swift-BAT refined analysis
  75. GRB 250101A: further SAO RAS optical observations
  76. GRB 250101A: LCO optical counterpart detection
  77. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  78. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  79. GRB 250101A: Swift/UVOT Detection
  80. GRB 250101A: 1.6m Mephisto multi-band optical followup
  81. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  82. GRB 250101A: LCOGT optical afterglow detection
  83. GRB 250101A: OASDG optical observations
  84. Fermi GRB 250101B: Global MASTER-Net observations report
  85. GRB 250101A: SAO RAS observations of optical brightening
  86. GRB 250101A: AKO Optical Afterglow Detection
  87. GRB 250101A: SAO RAS optical observations
  88. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  89. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  90. GRB 250101A: SVOM/C-GFT early optical observations
  91. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  92. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  93. GRB 250101A: Nanshan/HMT optical observations
  94. GRB 250101A : GIT optical detection
  95. GRB 250101A: GMG Optical Observation
  96. GRB 241217a/EP241217b: ATCA Radio Detection
  97. EP241217a: VLA Radio Detection

  98. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  99. GRB 241229B: Continued CrAO ZTSh observations
  100. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification

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