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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"

15742 results found.

  1. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  2. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  3. GRB 241002C : MITSuME Akeno optical upper limits
  4. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  5. GRB241001A: REM optical/NIR upper limits
  6. GRB 241002A: Swift/UVOT Upper Limits
  7. EP240930a: Liverpool Telescope observations
  8. GRB 241002A: LCOGT Optical Upper Limits
  9. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  10. GRB 241001A: Swift/UVOT Detection
  11. GRB 241001A: VLT/X-shooter redshift
  12. GRB 241002B: GOTO optical counterpart candidate
  13. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  14. GRB 241001A: Swift-XRT observations
  15. GRB241001A: optical afterglow candidate
  16. GRB 241002A: 1.5m OSN optical upper limit
  17. GRB 241001A: BOOTES-6/DPRT optical upper limit
  18. EP240930a : KAIT optical upper limit
  19. EP240930a: GOTO optical upper limits
  20. GRB 240929A : Leavitt Observatory optical upper limit
  21. GRB 240825A: LBT optical observations
  22. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  23. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  24. LIGO/Virgo S240919bn: GOTO optical upper limits
  25. EP240913A/GRB 240913C: AbAO optical upper limit
  26. EP240919a / GRB 240919A: Mondy optical upper limit
  27. EP240913a/GRB 240913C: 1.6m Mephisto observations
  28. EP240918a: SVOM/VT upper limit
  29. EP240919a / GRB 240919A: REM optical and NIR upper limits
  30. EP240919a / GRB 240919A: KAIT optical upper limit
  31. EP240918b and EP240918c: Optical upper limits with Kinder observations
  32. EP240919a: Optical upper limit with Kinder observations
  33. GRB 240910A: radio detection with the VLA
  34. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  35. EP240919a: NOT and Gemini optical observations
  36. EP240919a: GOTO optical upper limits
  37. EP240919a: JinShan optical upper limits
  38. EP240918a: JinShan optical upper limits
  39. EP240918a: YAHPT Optical Upper Limit
  40. EP240918a: Optical upper limits with Kinder observations
  41. EP240918a: GMG Optical Upper Limit
  42. GRB 240916A: NOT optical observation
  43. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  44. GRB 240916A: Fermi GBM Observation
  45. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  46. GRB 240916A: Swift-XRT afterglow detection
  47. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  48. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  49. EP240913a/GRB 240913C: KAIT optical upper limit
  50. GRB 240910A: SVOM/VT optical observations
  51. EP240913a: NOT optical upper limits
  52. EP240913a: JinShan optical upper limits
  53. EP240913a: ESO-NTT optical observations
  54. GRB 240914A: ESO-NTT optical observations
  55. GRB 240905E: further NOT optical observations
  56. GRB 240911A: LCO optical observations
  57. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  58. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  59. GRB 240912A: J-band observations with WINTER
  60. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  61. GRB 240912A: NOT optical spectroscopy
  62. Fast X-ray Transient EP240801a: GMRT radio observations
  63. GRB 240912A: Swift detection of a burst with an optical counterpart
  64. GRB 240910A: NOT optical observations
  65. GRB 240911A : a likely weak GRB detected by SVOM/ECLAIRs
  66. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  67. GRB 240910A: JinShan optical observations
  68. GRB 240910A: GOTO candidate optical counterpart
  69. EP240908a: Optical afterglow confirmation
  70. GRB 240825A: 7DT Optical Upper Limit
  71. GRB 240905E: SVOM/VT optical observations
  72. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  73. EP240908a: Mondy and AbAO follow-up observations
  74. EP240908a: Updates on the WXT detection result around the trigger time
  75. EP240908a: optical afterglow candidate
  76. EP240908a: TRT optical upper limit
  77. GRB 240905B: GOTO optical upper limits
  78. GRB 240905E: GIT optical upper limit
  79. GRB 240905E: Gaoyazi/GOT optical upper limits
  80. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  81. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  82. GRB 240905E: AKO Optical Upper Limit
  83. GRB 240905E: SVOM/C-GFT optical upper limit
  84. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  85. GRB 240905E: NOT optical upper limits
  86. GRB 240905E: REM optical/NIR upper limits
  87. GRB 240905E: LCOGT Optical Upper Limit
  88. GRB 240905E: Swift/UVOT Upper Limits
  89. GRB 240905E: SAO RAS optical upper limit
  90. GRB 240825A: Montarrenti Observatory optical follow-up observations
  91. GRB 240905E: Nanshan/HMT optical upper limit
  92. GRB 240819A: Optical upper limits from TESS
  93. GRB 240825A: ATCA Detection of Radio Counterpart
  94. GRB 240825A: Magnitude Correction in SVOM/C-GFT Optical Observations
  95. GRB 240825A: MeerLICHT afterglow detection
  96. GRB 240828A: SAO RAS AS-500(2) optical observations
  97. GRB 240821A: VLT spectroscopic observations
  98. GRB 240825A: TSHAO Optical Upper Limit
  99. GRB240828B: REM optical/NIR upper limits
  100. GRB 240828B: AbAO optical upper limit

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