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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"

15722 results found.

  1. GRB 250108B: Swift/UVOT Upper Limits
  2. GRB 250106A: SVOM/VT 2nd optical deep observation
  3. GRB 250101A: J band upper limit by SYSU 80cm telescope
  4. EPWXT01709129925: Xinglong optical observations
  5. GRB 250106A: NOT optical observations
  6. GRB 250103B: REM optical/NIR upper limits
  7. GRB 250101A: REM optical/NIR counterpart detection
  8. GRB 250106A: Swift-XRT observations
  9. GRB 250106A: SVOM/VT optical candidate
  10. GRB 241229A: SVOM/VT optical upperlimit
  11. GRB 250103B: LCO/1m optical afterglow candidate detection
  12. GRB 250103A: Bassano Bresciano Observatory upper limit
  13. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  14. GRB 250103A: Swift-XRT observations
  15. GRB 250101A: 1.3m DFOT optical afterglow detection
  16. GRB 241229A: 1.3m DFOT upper limit
  17. GRB 241228B: 1.3m DFOT Optical observations
  18. GRB 241228A: 1.3m DFOT upper limit
  19. GRB 250103A: NOT spectroscopic redshift
  20. GRB 250103B：SVOM/VT optical counterpart
  21. GRB 250103A: Montarrenti Observatory optical detection
  22. GRB 250101A: further LCOGT optical afterglow observations
  23. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  24. GRB 250103A: NOT optical observations
  25. GRB 250103A: TSHAO optical upper limit
  26. GRB 250103B: LCOGT Optical Upper Limit
  27. GRB 250103A: SVOM/VT optical counterpart confirmation
  28. EP250101a: Liverpool Telescope optical upper limit
  29. GRB 250101a: Liverpool Telescope optical follow-up
  30. GRB 250103A: Xinglong 2.16m Optical Candidate
  31. GRB 250101B: SVOM/GRM observation
  32. GRB 250103A: GOTO optical upper limit
  33. GRB 250103A: SVOM/C-GFT optical upper limit
  34. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  35. EP241231b: optical upper limit with the Liverpool Telescope
  36. EP250101a: Xinglong optical upper limit
  37. GRB 250101A: further SAO RAS optical observations
  38. GRB 250101A: LCO optical counterpart detection
  39. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  40. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  41. GRB 250101A: Swift/UVOT Detection
  42. GRB 250101A: 1.6m Mephisto multi-band optical followup
  43. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  44. GRB 250101A: LCOGT optical afterglow detection
  45. GRB 250101A: OASDG optical observations
  46. GRB 250101A: SAO RAS observations of optical brightening
  47. GRB 250101A: BOOTES-4/MET optical afterglow detection
  48. GRB 250101A: AKO Optical Afterglow Detection
  49. GRB 250101A: SAO RAS optical observations
  50. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  51. GRB 250101A: SVOM/C-GFT early optical observations
  52. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  53. GRB 250101A: Nanshan/HMT optical observations
  54. GRB 250101A : GIT optical detection
  55. GRB 250101A: GMG Optical Observation
  56. GRB 250101A: Swift detection of a burst with an optical counterpart
  57. GRB 241217a/EP241217b: ATCA Radio Detection
  58. GRB 241229B: Continued CrAO ZTSh observations
  59. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  60. GRB 241229B: SVOM/GRM observation
  61. EP241217A: J band upper limit by SYSU 80cm telescope
  62. GRB 241229B: SAO RAS optical upper limit
  63. GRB 241228B: SAO RAS optical observations
  64. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  65. GRB 241229A: SAO RAS optical observations
  66. GRB 241229B: SVOM/VT optical candidate
  67. EP240702a: 7DT Optical upper limits
  68. GRB 240606B: 7DT Optical upper limits
  69. GRB241229B: UVOT upper limits
  70. GRB 241228B: D50 optical detection
  71. GRB 241228B: Swift-XRT afterglow detection
  72. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  73. GRB 241228A: Mondy optical afterglow observations
  74. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  75. GRB 241229A: GOTO optical upper limits
  76. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  77. GRB 241228A: NOT optical upper limits
  78. GRB 241228B: LCO optical observation
  79. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  80. GRB241228B: GROWTH-India Telescope optical observations
  81. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  82. GRB 241228B: GOTO24jmz optical follow-up observations
  83. GRB 241228A: GROWTH-India telescope optical upper limit
  84. GRB 241228B: TRT optical counterpart confirmation
  85. GRB 241228A: Swift/UVOT Upper Limits
  86. GRB 241228B: GOTO possible optical counterpart candidate
  87. GRB 241217A/EP241217b: continued SOAR observations
  88. EP241223a: Mondy AZT-33IK optical observations
  89. GRB 241029A: LCO optical observation
  90. GRB 241223A: Swift-XRT observations
  91. GRB 241029A: AbAO AS-32 optical observations
  92. EP241223a
  93. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  94. GRB241113A: 7DT Optical upper limits
  95. GRB 241223A: GOTO optical observations summary
  96. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  97. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  98. GRB 241217A/EP241217b: SOAR afterglow detection
  99. EP241217a: Liverpool Telescope optical upper limit
  100. EP241021a: VLA radio detection

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