SIMBAD references

Two possible planetary nebulae (PN G035.5-00.4 and IRAS 18551+0159), one newly re-identified supernova remnant (SNR G35.6-0.4), and one H II region (G35.6-0.5) form a line-of-sight-overlapping complex known as G35.6-0.5. We analyze 21 cm H I absorption spectra toward the complex to constrain the kinematic distances of these objects. PN G035.5-00.4 has a distance from 3.8±0.4 kpc to 5.4±0.7 kpc. IRAS 18551+0159 is at 4.3±0.5 kpc. We discuss the distance for SNR 35.6-0.4, for which the previous estimate was 10.5 kpc, and find a plausible distance of 3.6±0.4 kpc. The new distance of SNR G35.6-0.4 and the derived mass for the ∼55 km/s CO molecular cloud can accommodate an association with HESS J1858+020. We also conclude that SNR G35.6-0.4 is unlikely to be associated with PSR J1857+0210 or PSR J1857+0212, which are projected onto the SNR area.