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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"

20821 results found.

  1. GRB 240821A: radio observation with the VLA
  2. GRB 240916A: Swift-XRT afterglow detection
  3. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  5. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  6. EP240913a: VLT/HAWK-I near-infrared upper limits
  7. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  9. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  10. GRB 240914A: Swift-XRT observations
  11. GRB 240910A: SVOM/VT optical observations
  12. EP240913a: NOT optical upper limits
  13. EP240913a: JinShan optical upper limits
  14. EP240913a: ESO-NTT optical observations
  15. GRB 240914A: ESO-NTT optical observations
  16. GRB 240905E: further NOT optical observations
  17. EP240913a: EP-WXT detection of a fast X-ray transient
  18. GRB 240911A: LCO optical observations
  19. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  20. GRB 240912A: Swift/UVOT Detection
  21. GRB 240911A: Swift-XRT observations
  22. GRB 240912A: J-band observations with WINTER
  23. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  24. GRB 240912A: Enhanced Swift-XRT position
  25. GRB 240912A: Redshift from OSIRIS+/GTC
  26. Fast X-ray Transient EP240801a: GMRT radio observations
  27. GRB 240910A: Redshift from OSIRIS+/GTC
  28. GRB 240912A: Swift detection of a burst with an optical counterpart
  29. GRB 240910A: JinShan optical observations
  30. IPN triangulation of GRB 240905B (short)
  31. GRB 240825A: 7DT Optical Upper Limit
  32. GRB 240905E: SVOM/VT optical observations
  33. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  34. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  35. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  36. GRB 240910A: SVOM/GRM observation
  37. EP240908a: Mondy and AbAO follow-up observations
  38. EP240908a: TRT optical upper limit
  39. EP240908a: EP detection of a fast X-ray transient
  40. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  43. GRB 240905E: GIT optical upper limit
  44. GRB 240905B: Swift-XRT observations
  45. GRB 240905E: Gaoyazi/GOT optical upper limits
  46. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  47. GRB 240905B: Fermi-LAT detection
  48. GRB 240905E: J-band observations with WINTER
  49. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  50. GRB 240905E: AKO Optical Upper Limit
  51. GRB 240905E: SVOM/C-GFT optical upper limit
  52. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  53. GRB 240905E: NOT optical upper limits
  54. GRB 240905E: REM optical/NIR upper limits
  55. GRB 240902B: AstroSat CZTI detection of a long burst
  56. GRB 240905E: LCOGT Optical Upper Limit
  57. GRB 240905E: Swift/UVOT Upper Limits
  58. GRB 240905E: SAO RAS optical upper limit
  59. GRB 240905E: Nanshan/HMT optical upper limit
  60. GRB 240905E: Swift detection of a burst
  61. GRB 240819A: Optical upper limits from TESS
  62. GRB 240904A: Swift detection of a burst
  63. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  64. GRB 240825A: MeerLICHT afterglow detection
  65. GRB 240828A: SAO RAS AS-500(2) optical observations
  66. GRB 240825A: TSHAO Optical Upper Limit
  67. GRB240828B: REM optical/NIR upper limits
  68. GRB 240828B: AbAO optical upper limit
  69. GRB 240825A: SOAR observations
  70. GRB 240828B: Mephisto optical upper limit
  71. GRB 240828B: GRANDMA Optical Upper Limit
  72. LIGO/Virgo/KAGRA S240830gn: Updated Sky localization and EM Bright Classification
  73. LIGO/Virgo/KAGRA S240830gn: Identification of a GW compact binary merger candidate
  74. GRB 240825A: MeerKAT detection
  75. GRB 240828B: J-band upper limit from WINTER
  76. GRB 240828B: GMG Optical Upper Limit
  77. GRB 240828B: SVOM/C-GFT optical upper limit
  78. GRB 240828B: SAO RAS optical upper limit
  79. GRB 240828A: SAO RAS optical observations
  80. GRB 240629A: First GRB Detected by BurstCube
  81. GRB 240828A: KAIT Optical Afterglow Candidate
  82. GRB 240825A: SVOM/VT optical detection
  83. GRB 240828A: Swift-XRT afterglow detection
  84. GRB 240825A: further SAO RAS optical observations
  85. GRB 240825A: iTelescope optical observations
  86. GRB 240828B: Swift-XRT afterglow detection
  87. GRB 240829A: Swift detection of a burst
  88. GRB 240828A: AstroSat CZTI detection of a long burst
  89. Fermi GRB 240828A: Bassano Bresciano Observatory upper limit
  90. GRB 240819A as a likely X-Ray Flash
  91. GRB 240821A: PRIME near-infrared observations
  92. GRB 240828B : Detection of a possible very soft X-ray transient by SVOM/ECLAIRs
  93. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  94. GRB 240825A: SAO RAS optical observations
  95. GRB 240824A: GIT optical upper limit
  96. GRB 240819A: Swift afterglow confirmation
  97. GRB 240825A: NUTTelA-TAO / BSTI Optical Limits
  98. GRB 240825A: GMG Continued Optical Observation on the Second Night
  99. GRB 240825A: PRIME near-infrared detection
  100. GRB 240825A : MISTRAL/T193 OHP optical follow-up of the afterglow

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