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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

19589 results found.

  1. EP250111a: NOT likely optical counterpart
  2. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  3. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  4. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  5. GRB 250101A: CMO RC-500 optical observations
  6. EP250108a: NOT optical observations
  7. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  8. GRB 250109a: GMG Optical Upper Limit
  9. EP250109a: Swift/UVOT non-detection
  10. IPN triangulation of GRB 250107D (short/hard)
  11. EP250108a: Liverpool Telescope likely optical counterpart
  12. GRB 250108B: Gemini-North likely redshift z = 2.197
  13. GRB 250108B: 1.3m DFOT upper limit
  14. GRB 250108B: REM optical/NIR upper limits
  15. EP250109a: Global MASTER-Net observations report
  16. GRB 250101A: Terskol K-800 optical observations
  17. EP250109a: Swift/XRT non-detection
  18. GRB 250108A: Swift/UVOT Upper Limits
  19. GRB 250108A: NOT optical upper limit
  20. EP250108a: EP-WXT detection of an X-ray transient
  21. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  22. GRB 250103A: 1.6m Mephisto optical observations
  23. GRB 250108A: Swift-XRT afterglow detection
  24. GRB 250108A:SVOM/VT optical candidate
  25. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  26. GRB 250108B: Swift/UVOT Upper Limits
  27. GRB 250103A: Swift-XRT afterglow detection
  28. GRB 250108B: Enhanced Swift-XRT position
  29. GRB 250108B: Swift detection of a burst
  30. GRB 250108A: Swift ToO observations
  31. GRB 250108A: SVOM detection of a soft long burst
  32. GRB 250107A: Swift ToO observations
  33. GRB 250101A: J band upper limit by SYSU 80cm telescope
  34. EPWXT01709129925: Xinglong optical observations
  35. GRB 250106A: NOT optical observations
  36. GRB 250103B: REM optical/NIR upper limits
  37. GRB 250101A: REM optical/NIR counterpart detection
  38. GRB 250106A: Swift ToO observations
  39. GRB 250106A: SVOM detection of a long burst
  40. GRB 250103B: Swift-XRT refined Analysis
  41. GRB 250103B: LCO/1m optical afterglow candidate detection
  42. GRB 250103A: Bassano Bresciano Observatory upper limit
  43. GRB 250101A: 1.3m DFOT optical afterglow detection
  44. GRB 241229A: 1.3m DFOT upper limit
  45. GRB 241228B: 1.3m DFOT Optical observations
  46. GRB 241228A: 1.3m DFOT upper limit
  47. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  48. GRB 250103A: Montarrenti Observatory optical detection
  49. GRB 250101A: further LCOGT optical afterglow observations
  50. GRB 250103A: TSHAO optical upper limit
  51. GRB 250103B: LCOGT Optical Upper Limit
  52. EP250101a: Liverpool Telescope optical upper limit
  53. GRB 250103A: Swift ToO observations
  54. GRB 250101a: Liverpool Telescope optical follow-up
  55. GRB 250103B: SVOM detection of a long burst
  56. GRB 250103B: Swift detection of a burst
  57. GRB 250103A: Xinglong 2.16m Optical Candidate
  58. GRB 250101B: SVOM/GRM observation
  59. GRB 250103A: GOTO optical upper limit
  60. GRB 250103A: SVOM/C-GFT optical upper limit
  61. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  62. EP241231b: optical upper limit with the Liverpool Telescope
  63. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  64. GRB 250103A: SVOM detection of a long burst
  65. EP250101a: Xinglong optical upper limit
  66. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  67. GRB 250101A: further SAO RAS optical observations
  68. GRB 250101A: LCO optical counterpart detection
  69. GRB 250101A: Swift/UVOT Detection
  70. GRB 250101A: 1.6m Mephisto multi-band optical followup
  71. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  72. GRB 250101A: LCOGT optical afterglow detection
  73. GRB 250101A: OASDG optical observations
  74. GRB 250101A: AKO Optical Afterglow Detection
  75. GRB 250101A: SAO RAS optical observations
  76. GRB 250101A: Enhanced Swift-XRT position
  77. GRB 250101A: SVOM/C-GFT early optical observations
  78. GRB 250101A : GIT optical detection
  79. GRB 250101A: GMG Optical Observation
  80. GRB 250101A: Swift detection of a burst with an optical counterpart
  81. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  82. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  83. GRB 241229B: Continued CrAO ZTSh observations
  84. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  85. GRB 241229B: SVOM/GRM observation
  86. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  87. EP241217A: J band upper limit by SYSU 80cm telescope
  88. GRB 241229B: SAO RAS optical upper limit
  89. GRB 241228B: SAO RAS optical observations
  90. EP240702a: 7DT Optical upper limits
  91. GRB 240606B: 7DT Optical upper limits
  92. GRB241229B: UVOT upper limits
  93. GRB 241228B: Swift-XRT afterglow detection
  94. GRB 241229A: Swift ToO observations
  95. GRB 241228A: Mondy optical afterglow observations
  96. GRB 241229A: GOTO optical upper limits
  97. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  98. GRB 241228A: NOT optical upper limits
  99. GRB 241228B: LCO optical observation
  100. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst

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