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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"

15983 results found.

  1. EP260806a: LCO likely optical counterpart
  2. SN 2026stf / GRB 260708A: ATLAS forced photometry
  3. AT 2026wki: EP/FXT follow-up observations
  4. GRB 260708A: LCO further optical observations show supernova features
  5. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  6. GRB 260802A: SVOM/VT optical upper limits from VHF data
  7. GRB 260802A: LCO optical upper limits
  8. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  9. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  10. EP260731a: COLIBRÍ optical upper limit
  11. EP260731a: NOT optical upper limit
  12. EP260728a: COLIBRÍ optical upper limit
  13. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  14. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  15. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  16. EP260727a: SAO RAS optical observations
  17. GRB 260727A: AbAO and SAO RAS optical observations
  18. GRB 260726A: EP-FXT follow-up observations
  19. GRB 260727A: SVOM/GRM observation
  20. GRB 260726A: Fermi GBM Observation
  21. EP260727a: 1.5m OSN optical counterpart detection
  22. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  23. EP260727a: OHP/T193 optical observations
  24. GRB 260726A: Liverpool Telescope optical observations
  25. GRB 260727A: Liverpool Telescope optical upper limits
  26. EP260727a: Liverpool Telescope confirmation of optical counterpart
  27. EP260727a: NUTTELA-TAO Early Optical Limits
  28. GRB 260727A: EP/FXT follow-up observations
  29. EP260727a: Einstein Probe detection of an X-ray transient
  30. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  31. GRB 260726A: J-band upper limit with WINTER
  32. GRB 260726A: SVOM/VT optical candidate
  33. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  34. GRB 260727A: GOTO early optical upper limit
  35. GRB 260727A: Kilonova-Catcher optical upper limit
  36. GRB 260727A: LCO optical upper limits
  37. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  38. EP260723a: further EP-FXT follow-up observation
  39. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  40. EP260723a: EP-FXT follow-up observation
  41. EP260723a: SVOM/VT optical observation
  42. EP260723a: COLIBRÍ optical observations
  43. EP260723a: NOT optical conterpart confirmation
  44. EP260723a: Liverpool Telescope likely optical counterpart
  45. GRB 260705A: Retraction of optical counterpart
  46. GRB 260718A: LCO optical upper limits
  47. GRB 260710A: SVOM/GRM observation
  48. GRB 260718A : GRANDMA and KNC upper limits
  49. GRB 260718A: SVOM/VT optical upper limits
  50. GRB 260718A: SVOM/VT optical upper limits from VHF data
  51. GRB 260714B: SVOM/GRM observation
  52. GRB 260618B: EP-FXT follow-up observation upper limit
  53. GRB 260714B: COLIBRÍ optical counterpart candidate
  54. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  55. GRB 260705A: ATCA radio observations
  56. GRB 260619A: SVOM/VT continuous optical observations
  57. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  58. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  59. EP260623a: KAIT optical observations
  60. GRB 260708A: GRANDMA Optical Observations
  61. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  62. GRB 260708A: LCO optical observations
  63. GRB 260709A: SVOM/GRM detection
  64. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  65. GRB 260708A: Glowbug gamma-ray detection
  66. GRB 260706A : GRANDMA Upper limits
  67. GRB 260708A: Kilonova-Catcher optical afterglow detection
  68. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  69. GRB 260705B: SVOM/GRM observation
  70. GRB 260706A: SVOM/VT optical upper limits
  71. EP260707a (by EP-FXT): NOT optical upper limit
  72. EP260707a is not a real source
  73. EP260707a: LCOGT Optical Upper Limit
  74. EP260707a: TRT optical upper limit
  75. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  76. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  77. GRB 260706A: REM optical/NIR observations
  78. IceCube-260704A: No candidates from the Zwicky Transient Facility
  79. GRB 260706A: LCO optical upper limit
  80. GRB 260706A: SVOM detection of a burst
  81. IceCube260704A: OHP/T193 optical observations
  82. GRB 260705A: LCO optical upper limits
  83. GRB 260704A: NOT optical upper limits
  84. GRB 260705A: SVOM detection of a burst
  85. GRB 260629A: SVOM/GRM observation of a short burst
  86. GRB 260610B: VLA detection
  87. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  88. EP260626a: further Liverpool Telescope optical upper limits
  89. EP260626a: EP-FXT follow-up observation
  90. EP260626a: COLIBRÍ optical upper limit
  91. EP260623a: FTW optical and NIR observations
  92. EP260623a: Liverpool Telescope optical observations
  93. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  94. EP260623a: WINTER J-band observations
  95. EP260623a: Optical follow-up observations with Kinder
  96. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  97. EP260623a: SVOM/VT optical observations
  98. EP260623a: TRT optical observations
  99. EP260623a: REM optical/NIR afterglow detection
  100. EP 260623a: COLIBRÍ optical observations

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