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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"

24993 results found.

  1. GRB 250101A: SAO RAS observations of optical brightening
  2. GRB 250101A: BOOTES-4/MET optical afterglow detection
  3. GRB 250101A: AKO Optical Afterglow Detection
  4. GRB 250101A: SAO RAS optical observations
  5. GRB 250101A: Enhanced Swift-XRT position
  6. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  7. GRB 250101A: SVOM/C-GFT early optical observations
  8. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  9. GRB 250101A: Nanshan/HMT optical observations
  10. GRB 250101A : GIT optical detection
  11. GRB 250101A: GMG Optical Observation
  12. GRB 250101A: Swift detection of a burst with an optical counterpart
  13. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  14. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  15. GRB 241229B: Continued CrAO ZTSh observations
  16. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  17. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  18. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  19. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  20. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  21. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  22. GRB 241229B: SVOM/GRM observation
  23. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  24. EP241217A: J band upper limit by SYSU 80cm telescope
  25. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  26. GRB 241229B: SAO RAS optical upper limit
  27. GRB 241228B: SAO RAS optical observations
  28. GRB 241229A: SAO RAS optical observations
  29. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 241229A: Swift-XRT observations
  31. EP240702a: 7DT Optical upper limits
  32. GRB 240606B: 7DT Optical upper limits
  33. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  34. GRB 241229B: Swift-BAT refined analysis
  35. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  36. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  37. GRB241229B: UVOT upper limits
  38. GRB 241228B: Fermi GBM Observation
  39. GRB 241228B: Swift-XRT afterglow detection
  40. GRB 241229B: Fermi GBM Observation
  41. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  42. GRB 241228A: Mondy optical afterglow observations
  43. GRB 241229A: GOTO optical upper limits
  44. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  45. GRB 241228A: NOT optical upper limits
  46. GRB 241228B: LCO optical observation
  47. GRB 241228A: Swift-BAT refined analysis
  48. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  49. GRB 241228A: Fermi GBM Observation
  50. GRB241228B: GROWTH-India Telescope optical observations
  51. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  52. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  53. GRB 241228A: GROWTH-India telescope optical upper limit
  54. GRB 241228B: TRT optical counterpart confirmation
  55. GRB 241228A: Swift-XRT refined Analysis
  56. GRB 241228A: Swift/UVOT Upper Limits
  57. GRB 241228A: Enhanced Swift-XRT position
  58. GRB 241228A: Swift detection of a burst
  59. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  60. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  61. GRB 241212A: VZLUSAT-2 detection
  62. EP241223a: Mondy AZT-33IK optical observations
  63. GRB 241029A: LCO optical observation
  64. GRB 241223A: Swift-XRT observations
  65. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  66. GRB 241029A: AbAO AS-32 optical observations
  67. GRB 241223A: Fermi GBM Detection
  68. Fermi trigger No 756678579: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  70. EP241223a
  71. EP241223a: EP-WXT detection of a fast X-ray transient
  72. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  73. GRB241113A: 7DT Optical upper limits
  74. GRB 241223A: GOTO optical observations summary
  75. GRB 241105A: JWST photometric observations of the host galaxy
  76. EP241217a: e-MERLIN radio observations
  77. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  78. The EP-WXT trigger 01709129287 is likely a flaring star
  79. EP241217a: Liverpool Telescope optical upper limit
  80. EP241021a: VLA radio detection
  81. GRB 241218A: Mondy AZT-33IK optical upper limit
  82. EP241217a : Leavitt Observatory optical upper limit
  83. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  84. EP241217a: 1.6m Mephisto multi-band optical observations
  85. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  86. GRB 241218A: Swift/UVOT Upper Limits
  87. EP241217a: optical upper limit with the Liverpool Telescope
  88. GRB 241209B: EP-FXT afterglow detection
  89. GRB 241218A: NOT optical upper limits
  90. GRB 241218A: Swift-BAT refined analysis
  91. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  92. EP 241217a: NIR detection with P200/WIRC
  93. EP 241217a: Possible J-band detection with WINTER
  94. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  95. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  96. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  97. GRB 241217A / EP241217b: NOT optical upper limits
  98. GRB 241218A: REM optical upper limit
  99. GRB 241217A/EP241217b: REM optical/NIR upper limits
  100. EP241217a: REM optical/NIR upper limits

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