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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"

16159 results found.

  1. GRB 241002B: Swift-XRT afterglow detection
  2. GRB 241002A: NOT optical upper limits
  3. IceCube-241006A: No candidates from the Zwicky Transient Facility
  4. GRB 241006A: GRANDMA optical upper limits
  5. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  6. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  7. GRB 240910A: LBT optical observations
  8. GRB 241006A: Swift/UVOT Upper Limits
  9. GRB 241006A: SVOM/VT follow-up and optical upper limit
  10. GRB 241001A: Swift-XRT afterglow detection
  11. GRB 240930B: SVOM/C-GFT optical upper limit
  12. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  13. GRB 241002B: Swift-XRT observations
  14. GRB 241002C: SVOM/C-GFT optical upper limit
  15. GRB 241002B: PRIME near-infrared detection
  16. GRB 241001A : SVOM/VT optical detection
  17. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  18. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  19. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  20. GRB 241002C : MITSuME Akeno optical upper limits
  21. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  22. GRB241001A: REM optical/NIR upper limits
  23. GRB 241002A: Swift/UVOT Upper Limits
  24. EP240930a: Liverpool Telescope observations
  25. GRB 241002A: LCOGT Optical Upper Limits
  26. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  27. GRB 241001A: Swift/UVOT Detection
  28. GRB 241001A: VLT/X-shooter redshift
  29. GRB 241002B: GOTO optical counterpart candidate
  30. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  31. GRB 241001A: Swift-XRT observations
  32. GRB241001A: optical afterglow candidate
  33. GRB 241002A: 1.5m OSN optical upper limit
  34. GRB 241001A: BOOTES-6/DPRT optical upper limit
  35. EP240930a : KAIT optical upper limit
  36. EP240930a: GOTO optical upper limits
  37. GRB 240929A : Leavitt Observatory optical upper limit
  38. GRB 240825A: LBT optical observations
  39. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  40. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  41. LIGO/Virgo S240919bn: GOTO optical upper limits
  42. EP240913A/GRB 240913C: AbAO optical upper limit
  43. EP240919a / GRB 240919A: Mondy optical upper limit
  44. EP240913a/GRB 240913C: 1.6m Mephisto observations
  45. EP240918a: SVOM/VT upper limit
  46. EP240919a / GRB 240919A: REM optical and NIR upper limits
  47. EP240919a / GRB 240919A: KAIT optical upper limit
  48. EP240918b and EP240918c: Optical upper limits with Kinder observations
  49. EP240919a: Optical upper limit with Kinder observations
  50. GRB 240910A: radio detection with the VLA
  51. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  52. EP240919a: NOT and Gemini optical observations
  53. EP240919a: GOTO optical upper limits
  54. EP240919a: JinShan optical upper limits
  55. EP240918a: JinShan optical upper limits
  56. EP240918a: YAHPT Optical Upper Limit
  57. EP240918a: Optical upper limits with Kinder observations
  58. EP240918a: GMG Optical Upper Limit
  59. GRB 240916A: NOT optical observation
  60. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  61. GRB 240916A: Fermi GBM Observation
  62. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  63. GRB 240916A: Swift-XRT afterglow detection
  64. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  65. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  66. EP240913a/GRB 240913C: KAIT optical upper limit
  67. GRB 240910A: SVOM/VT optical observations
  68. EP240913a: NOT optical upper limits
  69. EP240913a: JinShan optical upper limits
  70. EP240913a: ESO-NTT optical observations
  71. GRB 240914A: ESO-NTT optical observations
  72. GRB 240905E: further NOT optical observations
  73. GRB 240911A: LCO optical observations
  74. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  75. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  76. GRB 240912A: J-band observations with WINTER
  77. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  78. GRB 240912A: NOT optical spectroscopy
  79. Fast X-ray Transient EP240801a: GMRT radio observations
  80. GRB 240912A: Swift detection of a burst with an optical counterpart
  81. GRB 240910A: NOT optical observations
  82. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  83. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  84. GRB 240910A: JinShan optical observations
  85. GRB 240910A: GOTO candidate optical counterpart
  86. EP240908a: Optical afterglow confirmation
  87. GRB 240825A: 7DT Optical Upper Limit
  88. GRB 240905E: SVOM/VT optical observations
  89. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  90. EP240908a: Mondy and AbAO follow-up observations
  91. EP240908a: Updates on the WXT detection result around the trigger time
  92. EP240908a: optical afterglow candidate
  93. EP240908a: TRT optical upper limit
  94. GRB 240905B: GOTO optical upper limits
  95. GRB 240905E: GIT optical upper limit
  96. GRB 240905E: Gaoyazi/GOT optical upper limits
  97. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  98. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  99. GRB 240905E: AKO Optical Upper Limit
  100. GRB 240905E: SVOM/C-GFT optical upper limit

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